The basics of surge protection

From the generation of surge voltages right through to a comprehensive protection concept In dialog with customers and partners worldwide Phoenix Contact is a global market leader in the field of electrical engineering, electronics, and automation. Founded in 1923, the family-owned company now employs around 14,000 people worldwide. A sales network with over 50 sales subsidiaries and 30 additional global sales partners guarantees customer proximity directly on site, anywhere in the world. Our range of services consists of products associated with a wide variety of electrotechnical applications. This includes numerous connection technologies for device manufacturers and machine building, components for modern control cabinets, and tailor-made solutions for many applications and industries, such as the automotive industry, wind energy, solar energy, the process industry or applications in the field Iceland Finland Norway

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2 PHOENIX CONTACT The basics of surge protection We don't just want to support you with convincing solutions, but also to be on hand with help and advice.This includes basic information on the topics of technology and electronics that applies to all of us. In this brochure, you will gain an insight into the field of surge protection. Discover the most important facts in a nutshell. Discover what solutions there are for the diverse challenges facing this sector. Or deepen your knowledge of the context and background; something only the specialists know. We wish you – in the truest sense of the word – an exciting read!

The very latest solutions

At Phoenix Contact, particular The many years of experience in emphasis is placed on development this area means Phoenix Contact expertise and a high degree of excels, both in development and manufacturing capability. All key manufacturing. The accredited technologies, from full engineering, to in-house lightning and high-current tool manufacturing, metal processing, laboratory, the most sophisticated in and plastic production, right through the world, is just part of this. It lays to electronics development and the foundation for precise, constantly manufacturing are all available adjusted test procedures and basic in-house. Since 1983, Phoenix Contact research tailored to the application – has developed and manufactured surge and can therefore be implemented for protective devices and today is the solutions using current findings from technology leader in this area. The theory and practice. company provides many innovative Essentially, products with the solutions for every industry and highest quality levels and cutting-edge application, among others, for technology. • Power supply • Measurement and control technology • Data technology and • Transceiver systems

PHOENIX CONTACT 3 Questions and answers You probably have a great deal of questions – ranging from basic queries as to how surge voltages even occur, to technical details about grid systems or individual components of a surge protection concept, right through to the device itself. Here you can refer to:

What is a surge voltage? How does it occur? What makes up a consistent surge Section 1, Page 6 protection concept? Section 2.3 et seqq., Page 13

What damage can surge voltages cause? Section 1.5, Page 9 How can the quality of surge protective devices be (officially) verified? Section 3.3, Page 18 How does surge protection work? Section 4, Page 22 Section 2.1, Page 10

In which applications is surge What legal or standard requirements protection particularly important? are there for surge protection? Section 6, Page 28 Section 2.2, Page 11

Explanation of terms Section 7, Page 56

4 PHOENIX CONTACT Contents

1. Surge voltages 6 1.1 The phenomenon of surge voltage 6 1.2 Causes 7 1.3 Coupling types 8 1.4 Direction of action 8 1.5 Effects 9

2. Surge protection: what should be noted? 10 2.1 This is how surge protection works 10 2.2 Lightning and surge protection standards 11 2.3 Basic protective measures and equipment 13 2.4 Lightning protection zones 14 2.5 The protective circle principle 15

3. Classification and testing ofsurge protective devices 16 3.1 Requirements according to product standard IEC 61643 16 3.2 Key characteristics for surge protective devices 17 3.3 Maintenance and testing according to IEC 62305 18 3.4 Pulse and high-current testing technology 20

4. Quality features 22 4.1 CE declaration of conformity 22 4.2 Independent product certifications 23 4.3 Expertise in surge protection 24

5. The lightning monitoring system 26 5.1 Smart monitoring 26 5.2 Lightning current detection 27

6. Fields of application 28 6.1 Protection of AC systems 28 6.2 Protection of DC systems with linear voltage sources 40 6.3 Protection of photovoltaic systems 41 6.4 Protection of signal transmission circuits in MCR technology 46 6.5 Protection of signal transmission circuits in information technology 52 6.6 Protection of signal transmission circuits in telecommunications technology 54 6.7 Protection of signal transmission circuits in transceiver systems 55

7. Glossary 56

8 References 59

PHOENIX CONTACT 5 The basics of surge protection | Surge voltages

1 Surge voltages

Various types of surge voltages occur in electrical plants and electronic systems. They are differentiated mainly by their duration and power. Depending on the cause, a surge voltage can last a few hundred microseconds, hours or even days. The amplitude can range from a few millivolts to some ten thousand volts. The direct or indirect consequences of lightning strikes are one particular cause of surge voltages. Here, during the surge voltage, high surge currents with amplitudes of up to some ten thousand amperes can occur. In this case, the consequences are particularly serious. This is because the damaging effect first of all depends on the power of the respective surge voltage pulse.

1.1 The phenomenon of surge voltage

Every electrical device has a specific kilovolts, steep voltage increases and of time, can become a heavy financial dielectric strength. If the level of a differences are often the consequence. burden – especially in comparison to the surge voltage exceeds this strength, Surge protection is the only thing cost of a lightning and surge protection malfunctions or damage can occur. Surge that helps. Indeed, the operator of an concept. voltages in the high or kilovolt range electrical system generally replaces the are generally transient overvoltages material damage to the system with of comparatively short duration. They corresponding protection. However, the generally last from a few hundred difference in time between failure of the microseconds to a few milliseconds. system to maintenance represents a risk As the maximum amplitude of such in itself. This failure is often not covered transients can amount to several by insurance and, within a short period

6 PHOENIX CONTACT The basics of surge protection | Surge voltages

1.2 Causes

The typical duration and amplitude of the surge voltage varies depending on the cause.

Lightning strikes It is above all lightning strikes (lightning electromagnetic pulse, LEMP) that have the greatest potential for damage among all the causes of occurrence.They cause transient overvoltages that can extend across great distances and are often associated with high-amplitude surge currents. Even the indirect effects of a lightning strike can lead to a surge voltage of several kilovolts and result in a surge current of tens of thousands Fig. 1: Lightning strikes have an extremely high potential for destruction of amperes. In spite of the very brief duration – a few hundred microseconds to a few milliseconds – such an event circuits, very high currents can flow exchange leads to a brief surge voltage. can lead to total failure or even the within a few milliseconds. These This presents a hazard, especially for destruction of the affected installation. short- term current changes can lead to sensitive electronic components. transient overvoltages. Switching operations Switching operations (switching Electrostatic discharges electromagnetic pulse, SEMP) can Electrostatic discharges (ESD) occur generate induced surge voltages that if bodies with different electrostatic spread to supply lines. In the case potential approach each other and result of large switch-on currents or short in a charge exchange.A sudden charge

Fig. 2: Electric motors with high power induce surge voltages due to high switch-on currents Fig. 3: Electrostatic discharges present a danger, particularly to sensitive electronics

PHOENIX CONTACT 7 The basics of surge protection | Surge voltages

1.3 Coupling types

Surge voltages can reach a circuit in is located in this magnetic field, then various ways. In reality, it is usually a according to the induction principle, a case of an overlap between individual voltage difference occurs here due to coupling types. the change in the magnetic field strength.

Galvanic coupling Capacitive coupling Two circuits that are connected to each An electrical field occurs between two other in an electrically conductive way points with different potentials.The can directly and mutually influence each charge carriers of objects within this other. A change in the voltage or current field are aligned according to the field in a circuit generates a corresponding direction and strength, in line with the reaction in another circuit. physical principle of influence. As such, a potential difference also occurs within Inductive coupling the object, in other words, a voltage A rapidly rising flow of current through difference. a conductor generates a magnetic field, with quickly changing strengths around the conductor.If another conductor

1.4 Direction of action

Common mode voltage Normal-mode voltage (symmetrical (asymmetrical voltage) voltage, differential mode) In the first instance, common mode surge In the first instance, the symmetrical voltages present a hazard to objects that surge voltages present a hazard to are located between active potentials objects that are located between two (phases and neutral conductors) and the active potentials. ground potential.

L/+ L/+

UQ N/- N/-

UL UL PE PE

Fig. 4: Common mode voltage Fig. 5: Normal-mode voltage

8 PHOENIX CONTACT The basics of surge protection | Surge voltages

1.5 Eff ects

The German Insurance Association increase of approximately 20% become is not just a case of having effective (GDV) regularly publishes statistics, apparent. Insurers consider one of the protection for fire and personnel, but allowing conclusions to be drawn on causes to be that ever more sensitive also about excluding the possibility of the total losses resulting from various electronic devices are finding their large financial risk. causes. Following fires and storms, way into households. On average, an A further aspect that will underline lightning strikes and surge voltages cause individual strike or damage from a surge the need for lightning and surge the most damage. In 2012, their share of voltage amounted to €800 in 2013. This protection in the future is the increase damage to all insured items totaled 18%. is the highest level since statistics began. of lightning strikes, as shown by In other words, almost a fifth of insured For non-private systems, however, the statistics. Various studies have already damage can be traced back to a surge consequences of a failure are generally shown that as part of global climate voltage. much more serious, such as downtimes change, the frequency of storms is set Device failure or defects caused by or data loss. The failure of a device or to increase. This development is thereby surge voltages are more frequent than a machine that is used in a professional not only limited to regions which have expected. According to statistics from environment often leads to costs that not displayed a high risk of strikes to the GDV, surge voltages are in fact are many times higher than repairing the date, but extends to all regions on Earth. the most frequent cause of damage. defective device. These figures only apply to damage that For example, if a mobile resulted in fire. communication mast fails, the cost for Fig. 6 shows that the proportion of the operator can lie in the range of damage caused by lightning and surge several euros per second. Calculated voltages in 2013 has dropped by 20% over the course of a day, this in comparison to the previous year. corresponds to damages of more than The financial payments by insurance €100,000. providers, however, fell by just 10%. If For this reason, a consistent surge the values from the comparable year of protection concept is urgently required 2010 are taken as a basis, then a cost for industrial and business systems. It

340 million Insurance payments in euros

500,000 280 million

400,000

300,000

200,000

Number of damage cases 100,000

0 2006 2006 2008 2009 2010 2011 2012 2013

Fig. 6: Number of damage cases caused by lightning strikes and surge voltages and level of insurance payments

PHOENIX CONTACT 9 2 Surge protection: what should be noted?

Effective surge protection is not just simply installed. It has to be individually coordinated – to the system that is to be protected and the ambient conditions that are prevalent on site. For this reason, the design and concept must be consistent. This means many details must be taken into account, from considering the standards and stipulations right through to classification according to lightning protection zone.

2.1 This is how surge protection works

Surge protection should ensure that The way in which the surge protection surge voltages cannot cause damage to works can be easily explained by means installations, equipment or end devices. of the equipment's power supply diagram As such, surge protective devices (Fig. 7). (SPDs) chiefly fulfil two tasks: As described in Section 1.4, a surge • Limit the surge voltage in terms voltage can arise either between of amplitude so that the dielectric the active conductors as normal- strength of the device is not mode voltage (Fig. 8) or between exceeded. active conductors and the protective • Discharge the surge currents conductor or ground potential as associated with surge voltages. common mode voltage (Fig. 9).

L/+ L/+ L/+

N/- N/- N/-

PE PE PE

Fig. 7: Schematic power supply of a piece of Fig. 8: Effects of a surge voltage as normal-mode Fig. 9: Effects of a surge voltage as common equipment voltage mode voltage

10 PHOENIX CONTACT With this in mind, surge protective devices are installed either in parallel L/+ to the equipment, between the active L/+ N/- conductors themselves (Fig. 10) or SPD between the active conductors and the N/- SPD protective conductor (Fig. 11). A surge protective device functions in PE PE the same way as a switch that turns off the surge voltage for a brief time. By doing so, a sort of short circuit occurs; surge currents can flow to ground or to the supply network. The Fig. 10: SPD between the active conductors Fig. 11: SPD between active conductors and the voltage difference is thereby restricted protective conductor (Fig. 12 and 13). This short circuit of sorts only lasts for the duration of the surge voltage event, typically a few microseconds. The equipment to be L/+ protected is thereby safeguarded and L/+ continues to work unaffected. N/- SPD N/- SPD

PE PE

Fig. 12: SPD between the active conductors in Fig. 13: SPD between active conductors and the case of normal-mode voltage the protective conductor in the case of common mode voltage

2.2 Lightning and surge protection standards

National and international standards • Protective measures against provide a guide to establishing a lightning atmospheric influences or switching and surge protection concept as well as operations: IEC 60364-4-44 [5] the design of the individual protective deals with this. In comparison with devices. A distinction is made between IEC 62305, it is based on a shortened the following protective measures: risk analysis and uses this as the basis • Protective measures against lightning for deriving corresponding measures. strike events: lightning protection In addition to the standards mentioned, standard IEC 62305 [1] [2] [3] [4] if applicable, other legal and deals with this. A key component of country- specific stipulations are also to this is an extensive risk assessment be considered. regarding the requirement, scope, and cost-effectiveness of a protection concept.

PHOENIX CONTACT 11 The basics of surge protection | Surge protection: what should be noted?

2.2.1 Lightning protection cost for a lightning protection system that can be conducted away safely according to IEC 62305 compare to the costs of potential depending on the lightning protection damage without a protection system? level. This is described by means of Part 1: Characteristics of lightning The cost evaluation is based on the Lightning Protection Levels I to IV. strikes outgoings for the planning, assembly, and In Part 1 of this standard [1], the maintenance of the lightning protection characteristic properties of lightning system. strikes, the likelihood of occurrence, and the potential for hazard are taken into Parts 3 and 4: Planning aids and account. specifications If the risk assessment determines that Part 2: Risk analysis lightning protection is required and cost- The risk analysis according to Part 2 of effective, then the type and scope of the this standard [2] describes a process specific measures for protection can be with which, first of all, the need for planned based on Parts 3 [3] and 4 [4] lightning protection for a physical of this standard. The lightning protection system is analyzed. Various sources of level determined by risk management is damage, e.g., a direct lightning strike in decisive for determining the type and the building, come into focus, as do the scope of the measures. types of damage resulting from this: For physical structures that require an • Impact on health or loss of life extremely high level of safety, almost all • Loss of technical services for the strikes must be captured and conducted public away safely. For systems where a higher • Loss of irreplaceable objects of residual risk is acceptable, strikes with cultural significance lower amplitudes are not captured. • Financial losses Fig. 14 shows the lowest peak value of The financial benefits are determined strikes that can still be captured safely as as follows: how does the annual total well as the highest peak value of strikes

I 3 – 200 kA 99% of lightning

II 5 – 150 kA 97 %

III 10 – 100 kA 91 %

IV 16 – 100 kA 84 %

i/[kA] 10 50 100 150 200

Fig. 14: Lightning Protection Levels

12 PHOENIX CONTACT The basics of surge protection | Surge protection: what should be noted?

2.2.2 Surge protection Likewise, structural systems with an • Industrial or business activities, e.g., according to explosion risk as well as structural hotels, banks, production systems, IEC 60364-4-44 applications that could cause damage farms to the environment (e.g., petrochemical In all other cases, a risk assessment This standard [5] describes the systems or nuclear power plants) are must be carried out in line with the conditions in which surge protective not included in the application of the international standard. devices are to be used in low-voltage standard. For these processes, lightning systems to protect the electrical strike standard IEC 62305 is to be used installation against surge voltages. The exclusively. area of application is thereby limited to Surge protective devices should be surge voltages caused by atmospheric used if transient overvoltages could have influences or as a consequence effects on the following: of switching procedures that are • Human lives, e.g., safety systems, transmitted by the power supply system. hospitals Direct lightning strikes in a structural • Public and cultural institutions, e.g., system are not considered, only strikes loss of public services, IT centers, in or in the vicinity of supply lines. museums

2.3 Basic protective measures and equipment

In order to consistently protect a Lightning Protection Level is the basis The location of the interception units structural system from lightning strikes for this. This is derived from the risk on the building also has to be decided. and surge voltages, various protective analysis. If there are no regulations or There are three methods of doing so: measures or equipment that are tailored specifications for the external lightning • Rolling sphere method to one another are required. A broad protection, a minimum of Lightning • Protective angle method division can be made as follows: Protection Level III is recommended. • Mesh method • External lightning protection • Internal lightning protection • Grounding and equipotential bonding • Coordinated SPD system

2.3.1 External lightning protection

External lightning protection (Fig. 15) aims to divert strikes which come near to the object to be protected and to transmit the lightning current from the point where it hits to ground. As such, no damage can be caused by means of thermal, magnetic or electrical effects. External lightning protection is systematic: it consists of the air-terminal, the arresters, and the grounding system. Part 3 of standard IEC 62305 [3] is crucial when it comes to planning and erecting external lightning protection systems. Identifying and determining the Fig. 15 External lightning protection, on the outside of a private residence, for example

PHOENIX CONTACT 13 The basics of surge protection | Surge protection: what should be noted?

2.3.2 Internal lightning 2.3.3 Grounding and • Incorporate all lines that cross protection equipotential bonding between different zones into the local equipotential bonding using suitable The internal lightning protection The grounding system aims to distribute SPDs system should prevent dangerous spark and discharge the captured lightning • Coordinate different types of formation inside the system. Sparks can current to ground. Here, the type of SPDs: the devices must address be caused by lightning current in the grounding system is more important each other selectively in order to external lightning protection system than the grounding resistance. The prevent individual components from or in other conductive parts of the lightning current is a very short pulse overloading structural system. that behaves like a high-frequency • Use short supply lines for the parallel The internal lightning protection current. Effective equipotential bonding connection of SPDs between active system consists of equipotential bonding is also important. Equipotential bonding conductors and the equipotential and the electrical insulation of external connects all electrically conductive parts bonding lightning protection systems. with each other via conductors – • Lay protected and unprotected lines Lightning protection equipotential active conductors are protected by separately bonding is a combination of measures surge protective devices. By doing so, • Only ground equipment via the that prevent potential differences. They it protects against all types of couplings. respective SPD (recommended) mainly connect the lightning protection system to metal installations, internal 2.3.4 Coordinated SPD system systems, as well as electrical and electronic systems within the system. A coordinated SPD system is This occurs by means of equipotential understood to be a multi-level system bonding lines, surge protective devices of surge protective devices that are or isolating spark gaps. coordinated with each other. To insulate the external lightning The following steps are recommended protection system, a minimum distance in order to achieve a high-performance between electrical lines and metal SPD system. installations must be kept, referred to • Divide the structural system into as the separation distance. lightning protection zones

2.4 Lightning protection zones

Deciding where to install surge LPZ 0A LPZ 1 protective devices within a structural Unprotected area outside a building Area inside the building which may system is based on the lightning in which direct lightning strikes are a still be subjected to high-energy surge protection zone concept explained possibility. Direct coupling of lightning voltages or surge currents and strong in Part 4 of the lightning protection currents in lines, unattenuated magnetic electromagnetic fields. standard IEC 62305 [4]. field of the lightning strike. It divides structural systems into LPZ 2 lightning protection zones (LPZ), and LPZ 0B Area inside a building which may still does so from outside to inside with Area outside the building that is be subjected to surge voltages or surge decreasing lightning protection levels. In protected from direct lightning strikes by currents and electromagnetic fields that external zones only resistant equipment means of an air-terminal. Unattenuated have already been significantly weakened. can be used. However, in internal zones, magnetic field of the lightning strike, sensitive equipment can also be used. only induced surge currents on lines. The individual zones are characterized and named as follows:

14 PHOENIX CONTACT The basics of surge protection | Surge protection: what should be noted?

LPZ 3 Area inside the building which may only be subjected to extremely low or hardly any surge voltages or surge currents and very weak or non-existent electromagnetic fields.

All lines that cross between zones must use coordinated surge protective devices (Fig. 16). Their power values are based on the protection class to be achieved, which is determined according to legal specifications or by means of the risk analysis. When it comes to selecting surge protective devices, use the standard as a basis, assuming that 50% of the lightning current will be discharged to ground. The other 50% of the lightning current is directed to the electrical installation via the main equipotential bonding and from there must be conducted away from the SPD system.

Fig. 16: Lightning protection zone concept

2.5 The protective circle principle

A clear depiction of the lightning The protective circle must protection zone concept is shown by the include all electrical and protective circle in Fig. 17. An imaginary electronic transmission lines circle should be drawn around the in the following areas: object to be protected. Surge protective • Power supply devices should be installed at all points • Measurement and control where cables intersect this circle. The technology area within the protective circle is • Information technology therefore protected in such a way that • Transceiver systems conducted surge voltage couplings are prevented. Fig. 17: Protective circle

PHOENIX CONTACT 15 The basics of surge protection | Classification and testing of surge protective devices

3 Classifi cation and testing of surge protective devices

Surge protective devices must provide defined protective functions and performance parameters in order to be suitable for use in corresponding protection concepts. As such, they are developed, tested, and classified according to their own international series of product standards. Yet even during use at a later stage, proper operation and therefore adherence to the protective function must be checked at regular intervals, as is also required of other safety-related components in electrical installations and electronic systems.

3.1 Requirements according to product standard IEC 61643

Surge protective devices/SPDs are power systems – Requirements and generally classified according to test methods for surge protective performance values, depending on the devices to be used in photovoltaic protection class and location of use, and installations [8] following product standard IEC 61643. In future, this series will be extended by In contains definitions of terms, general the following: requirements, and testing procedures for • IEC 61643-41: Surge protective surge protective devices. The standard devices connected to low-voltage distinguishes between: DC systems – Requirements and test • IEC 61643-11: Surge protective methods devices connected to low-voltage power systems – Requirements and test methods [6] • IEC 61643-21: Surge protective devices connected to telecommunications and signaling networks – Performance Fig. 18: IEC 61643 – requirements and testing methods [7] the product standard • IEC 61643-31: Surge protective for surge protective devices devices connected to low-voltage

16 PHOENIX CONTACT The basics of surge protection | Classification and testing of surge protective devices

3.2 Key characteristics for surge protective devices

Nominal voltage (UN) Maximum continuous voltage (Uc) Nominal discharge current (In) The nominal value of the voltage of the Maximum r.m.s. value of the voltage that Peak value of the current flowing current or signal circuit based on the use can continuously be applied to the mode through the SPD with pulse shape envisaged for the SPDs. of protection of the SPDs. (8/20 μs). The nominal voltage stated for an The maximum continuous voltage The pulse shape (8/20 μs) of a surge SPD corresponds to the system voltage must be at least 10% higher than the current is characteristic of the effects of of the typical SPD installation site for value of the nominal voltage. In systems an indirect lightning strike or switching a standard three-phase system, e.g., with greater voltage deviations, SPDs operation. The value of the nominal 230/400 V AC. Lower system voltages must be used where a greater difference discharge current is used for a variety of can also be protected by the SPD. In the is exhibited between Uc and Un. tests on an SPD, including those used to event of higher system voltages, it must determine the voltage protection level. be decided on a case-to-case basis as Voltage protection level (Up) Depending on the Lightning Protection to whether the SPD can be used and if Maximum voltage that can occur on Level assigned to a lightning protection there are restrictions to observe. the connection terminal blocks of the system, the SPDs must have minimum SPDs while loaded with a pulse of values that correspond to this value. Nominal load current (IL) specific voltage steepness and load with Maximum r.m.s. value of the nominal a discharge surge current of specified Off-load voltage (UOC) current, which allows a connected ohmic amplitude and wave form. Off-load voltage of the hybrid generator load to flow to one of the protected This value characterizes the surge at the terminal points of the SPD. outputs of the SPD. voltage protective effect of the A hybrid generator creates a This maximum value is specified by SPDs. In the event of a surge voltage combined surge; e.g., in off-load, it the parts carrying operational current phenomenon within the performance supplies a voltage pulse with a defined within the SPDs; these must be able parameters of the SPD, the voltage is pulse shape, generally (1.2/50 μs), and to withstand the continuous thermal safely limited to a maximum of this value in a short circuit, a current pulse with a current load. at the protected connections of the SPD. defined pulse shape, generally (8/20 μs). The combined surge is characteristic Short-circuit withstand capability Pulse discharge current (Iimp) of the effects of an induced surge (ISCCR) Peak value of the current flowing voltage. Depending on the protection Maximum uninfluenced short-circuit through the SPD with pulse shape class assigned to a lightning protection current of the electrical network, for (10/350 μs). system, the SPDs must have minimum which the SPD is rated in conjunction The pulse shape (10/350 μs) of a values that correspond to this value. with the upstream overcurrent surge current is characteristic of the protective device. effects of a direct lightning strike. The short-circuit withstand capability The value of the pulse discharge indicates up to which prospective current is used for special SPD tests short-circuit current the SPD can be to demonstrate carrying capacity with used at the installation location. The regard to high-energy lightning currents. corresponding tests to determine this Depending on the Lightning Protection value are carried out in connection with Level assigned to a lightning protection the upstream overcurrent protective system, the SPDs must have minimum device (or overcurrent protective device, values that correspond to this value. OCPD). In the event that the special surge protective devices for photovoltaic systems correspond to the value ISCPV, this is the maximum direct current short-circuit current of a system up to which the the SPD may be used.

PHOENIX CONTACT 17 The basics of surge protection | Classification and testing of surge protective devices

Normative surge current pulses steep. Consequently, the voltage-limiting manufacturer. This pulse shape contains The voltage-limiting function of the SPDs function of the SPD must be applied at several times the electrical load in is tested using surge currents with a very short notice. comparison to the (8/20 μs) pulse shape, pulse shape of (8/20 μs) (Fig. 19), i.e., SPDs that are designed to protect at the same amplitude. It therefore with a rise time of 8 μs and a decay time against direct lightning currents are places a considerably higher load on the to half value of 20 μs. This particularly additionally loaded with surge currents SPD in terms of energy. dynamic pulse shape also provides with a pulse shape of (10/350 μs) information regarding the response (Fig. 20). behavior of the SPD. The voltage rise The maximum amplitude is based on the associated with this surge current is very pulse discharge current specified by the

100 100 I 90 I (%) (%)

60 50

30

10 10

0 0 8 10 350 20 t (µs) t (µs)

Fig. 19: Course of a (8/20 μs) pulse Fig. 20: Course of a (10/350 μs) pulse

3.3 Maintenance and testing according to IEC 62305

To achieve high system availability, systems – internal and external a lightning protection expert. Inspecting system operators must regularly lightning protection – is required as the SPDs is also part of this. The inspect and maintain their electrical part of lightning protection standard standard also demands that maintenance systems (Table 1). This is stipulated by IEC 62305- 3 [3], also in Appendix E.7. is properly documented. The three legislators, supervisory authorities or Specialist knowledge is required in following points are particularly professional associations based on the order to carry out professional testing important to note: respective system type. Regular testing of lightning protection systems. For this and maintenance of lightning protection reason, this test must be carried out by

Visual check Comprehensive testing Comprehensive testing in critical Lightning Protection Level (years) (years) situations (years)

I and II 1 2 1 III and IV 2 4 1

Table 1: Testing intervals according to IEC 62305

18 PHOENIX CONTACT The basics of surge protection | Classification and testing of surge protective devices

• “Comprehensive testing in critical Advantages values is stored in a failsafe manner and situations” relates to structural The intelligent test device with a can be saved on a USB stick via a USB systems that contain sensitive systems modular design is equipped with an interface. It can be further processed or systems with a higher number of operating screen, a barcode scanner, using standard Office software (MS personnel. and a programmable logic controller as Word, MS Excel, etc.). • Explosion-protected, structural well as a current-limiting, high-voltage systems should undergo a visual check power supply unit that can be controlled every 6 months. The electrical test of remotely. Thanks to the use of test the installations should be carried out adapters, the CHECKMASTER 2 can once a year. easily be adjusted to different surge • For systems with strict requirements protection devices. These test adapters in terms of safety technology, for are easy to swap without tools and example, the legislator can prescribe there is no need to switch off the test a comprehensive check. This can be device. necessary if there has been a lightning The CHECKMASTER 2 not only strike within a certain radius of the detects defective surge protective CHECKMASTER 2 respective system. devices. It is also able to detect The CHECKMASTER 2 enables previously damaged surge protective convenient, fully-automated testing 3.3.1 Electrical test devices, where the electrical parameters of pluggable surge protective are at the limit of the defined tolerance devices. Surge protective devices At this point the question arises as to range. that are defective or already exhibit what exactly should be covered by a In order to also be able to check damage are safely detected and can comprehensive test. A visual check alone surge protective devices that will be be preventatively replaced. All test often cannot reliably provide an idea of developed in the future, software results are documented in line with the functional efficiency of an SPD. An updates can be carried out via USB standards. electrical test, however, can clearly show stick. These are available for component the performance capacity of the SPD. databases, the firmware, and operating When carrying out the electrical test languages. of SPDs, the test voltage is selected The test record with test results, in such a way as to make the SPD installation locations, and alphanumerical conductive. The measurement results are then compared to reference values and evaluated.

3.3.2 CHECKMASTER 2 test device

The CHECKMASTER 2 (Fig. 21) is a portable, robust, and safe to operate high-voltage testing device from Phoenix Contact for pluggable surge protective devices. It carries out an automatic, electrical test of pluggable SPDs.

Fig. 21: CHECKMASTER 2 high-voltage test device

PHOENIX CONTACT 19 The basics of surge protection | Classification and testing of surge protective devices

3.4 Pulse and high-current testing technology

Surge protective devices are more effective the more precisely they are tailored to the requirements and peculiarities of your area of application. The development of surge protective devices therefore demands laboratory iImpulse Ip simulation of the operating conditions – or more specifically, the electrical Surge U 50 Hz MV current conditions, as well as the surge voltage Power supply system generator SPD events.

Realistic simulation of surge voltage events For the test-based technical certification of high-performance SPDs of all types, high-performance low-voltage power Fig. 23: Three-phase 50 Hz high-current testing system for simulating different low-voltage power supply systems must be simulated. supply systems This simulation is coupled to a surge current generator in order to create transient surge voltage events. It is only protective device is subjected to surge Simulation of lightning surge with a test arrangement of this type current pulses, while it is simultaneously currents that the performance of the protective connected to a specifically parameterized Surge current generators (Fig. 26) are devices can be determined, as well as power supply system. The basic structure key components of the high-current their interactions with different power of such a testing system, which generally laboratory: they help to determine the supply systems. The IEC 61643-11 [6] consists of surge current generator, surge discharge capacity, test components standard describes a testing procedure protective device, and line-frequency for external lightning protection, and in this context which is referred to as power supply system, is depicted in also demonstrate the function of a work test. During this test, the surge Fig. 23. comprehensive surge voltage protection

Fig. 22: Resistance and inductance on the high- and low-voltage side of the Fig. 24: Testing stations of the high-current testing system testing transformer

20 PHOENIX CONTACT The basics of surge protection | Classification and testing of surge protective devices

Fig. 25: Fully automated testing system for determining the overload and Fig. 26: Lightning surge current generator failure behavior of surge protective devices according to IEC 61643-11 [6]

concepts. They simulate lightning surge of quality assurance, as well as the currents with amplitudes of up to independence and impartiality of 100 kA and switching surge currents the testing criteria. The essential with amplitudes of 200 kA and above. requirements in terms of expertise for The pulse shapes used in this context testing and calibration laboratories are are specified as (10/350 μs) pulses and described in DIN EN ISO/IEC 17025. are described in IEC 62305-1 [1]. The implementation and adherence to the standards may, for example, be Fully automated testing checked and confirmed by the German The requirements placed on surge Accreditation Body, DAkkS. protective devices in line with IEC 61643-11 [6] demand tests (Fig. 25) that assess overload and failure behavior. A key test that simulates aging of the surge protective device as a result of Laboratory operation at the highest level increasing leakage currents is the test • Every surge voltage event can be • Testing results that are easy of thermal stability. This test can take simulated. Phoenix Contact can to reproduce, efficient testing several hours. Similar time-intensive and simulate all low-voltage power operation. The Phoenix Contact resource-intensive testing sequences are supply systems with realistic laboratory is automated to a high defined in IEC 61643-21 [7] for SPDs for characteristics – using its in-house, degree and is therefore suitable use in signal transmission circuits. three-phase 50 Hz high-current for ongoing quality monitoring. testing system. It generates • Demonstrably the highest, Accreditation according to maximum short-circuit currents independently verified quality. DIN EN ISO /IEC 17025 of up to 50,000 A. Furthermore, Phoenix Contact's pulse It is not only the technical equipment the testing parameters can be very and high- current laboratory of the testing laboratory that counts: finely graduated and adjusted – the is accredited according to DIN EN ISO/IEC 17025. it is also the technical expertise of ideal basis for developing tailor-made the employees, the effectiveness of surge voltage protection systems. the management system in terms

PHOENIX CONTACT 21 The basics of surge protection | Quality features

4 Quality features

The quality and performance of surge protective devices are hard for a customer to assess. Correct functioning can only be tested in suitable laboratories. Besides the external appearance and haptics, only the technical data provided by the manufacturer can provide any guidance. Even more important is a reliable statement from the manufacturer regarding the performance of the SPD and the execution of the tests specified in the respective product standard from series IEC 61643.

4.1 CE declaration of conformity

An initial statement of quality is the CE evaluation of the product by a third declaration of conformity. It documents party. The CE mark only means that the the fact that the product complies with manufacturer has confirmed adherence the 2014/35/EU low-voltage directive to the relevant regulations with regard issued by the European Union. For surge to their product. If non-adherence to protective devices, fulfilling product the relevant regulations or misuse of standards from the EN 61643 series, the CE marking is proven, legal steps which are based on IEC 61643, is a can be initiated that may even result in prerequisite. prohibition of market launch under the Please note: the CE conformity European Union's supervision. assessment and declaration is issued by the manufacturer. It is therefore by no means a seal of approval by an independent institute or other attestation of an examination or Official CE logo to mark products

22 PHOENIX CONTACT The basics of surge protection | Quality features

4.2 Independent product certifi cations

A true mark of quality is a product and therefore also the confirmation of for the European Economic Area. It certification from an independent performance specifications is becoming is the same as the CE declaration of testing institute. These can also confirm increasingly important. conformity and can also be extended on fulfillment of the respective product this basis. standard. Furthermore, they can also KEMA, VDE, ÖVE, and more document additional characteristics This seal, issued by independent testing GL, ATEX, IECEX, and more of the products, such as resistance to institutes, confirms that the current These approvals verify the behavior the effects of shocks and vibrations or version of the respective product of the products in specific ambient safety requirements of specific domestic standard from the IEC 61643 series is conditions. markets. fulfilled. GL certifies the products' resistance The regulatory requirements to external influences in the maritime placed on SPDs sometimes require UL, CSA, EAC, and more environment as well as at sea, e.g., highly complex tests that only a few These approvals are examples of the shocks, vibrations, humidity or salt testing laboratories in the world are requirements of specific domestic concentration levels. fully capable of carrying out. For ever markets. ATEX and IECEx in turn confirm the more manufacturers and providers of What's more, in their own standards, products' suitability for use in potentially SPDs, specifically in the lower pricing UL and CSA place safety requirements explosive areas, such as those that segment, the specifications regarding on the products for the North American frequently arise in the process industry. the performance of the devices are markets or areas influenced by American also to be taken into account. As such, markets. In contrast, EAC is rather an the independent certification of SPDs administrative approval of the products

Independently verified quality Phoenix Contact furnishes a large part of its surge protection product range with independent certifications. By doing so, compliance with standards and maximum product quality is documented for the user.

Fig. 27: Product certifications by independent testing institutes

PHOENIX CONTACT 23 The basics of surge protection | Quality features

4.3 Expertise in surge protection

Application know-how • Develop and master innovative basic Measures to ensure quality are critical The further development of electrical technologies and should be carried out in series systems and system technology always • Structure development processes manufacturing as part of routine leads to new technologies, and as a • Develop new protection concepts testing. For surge protective devices, consequence of this, to completely as well as devices with tailor-made destructive testing that records the innovative technical solutions that place properties product characteristics right to the very specific requirements on surge performance limit and beyond can protection. One example is the system Testing and certification be useful. In this way, any possible technology that is used for renewable Testing systems that simulate real deviations in manufacturing processes energies (photovoltaics and wind conditions are essential in order to and consequently in product quality can power). For this reason it is important develop surge protection concepts and be detected at an early stage. to really understand the system to be devices. This also applies to technical protected and its environment, in order laboratory trials. to develop tailor-made surge protective devices. Manufacturing and quality assurance Research and development Manufacturing surge protective devices The basis for ongoing development is suitable for the market with the highest intensive commitment to fundamental quality levels demands that many aspects research and technological development. relating to processes and procedures The following tasks are part of this: are taken into account during the • Determine the precise requirements development phase of these products. placed on surge protective devices This requires early interlinking of (protection objectives) product development activities with • Make new, appropriate materials process and procedure development. available for applications

Fig. 28: Practical application Fig. 29: Development shaped by research

24 PHOENIX CONTACT The basics of surge protection | Quality features

Fig. 30: Quality assurance in the production process Fig. 31: Realistic testing conditions

A partner with experience and expertise Benefit from many advantages with • Close interlinking of product, Phoenix Contact as your solution procedure, and process provider in the field of surge development makes it possible protection: to implement all manufacturing • Basic research and technological aspects that are required in order development in-house, which open to guarantee products at the up technologies and materials for highest quality level from the word surge protection in a targeted way go, when the product is created. and make them usable. • Standardized quality tests that are • Product development as part of a carried out as automated routine network, driven by collaborations testing alongside the manufacturing with technology developers and process or batch-based tests within universities as well as active the scope of a destructive sample involvement in relevant national test, ensuring products with the and international prizes and highest level of safety and quality. working groups. • Operation of an in-house pulse and high-current laboratory accredited by ISO/IEC 17025, which makes it possible to fully qualify surge protective devices in accordance with all current standards in the area of lightning and surge protection.

PHOENIX CONTACT 25 The basics of surge protection | The lightning monitoring system

5 The lightning monitoring system

Lightning strikes cause devastating damage to buildings and systems. They are a particular hazard for exposed structures such as offshore wind parks, radio masts, leisure facilities or high buildings. It is practically impossible for employees to continuously monitor exposed or large-scale systems, which means that damage is detected too late.

The LM-S lightning monitoring system can detect and analyze lightning strikes in real time. It provides information online about the intensity of the strike based on the typical lightning parameters. By consolidating the system operating parameters and the measuring data, the system provides a better basis for making decisions regarding control and maintenance.

5.1 Smart monitoring

Lightning strikes can cause devastating destruction to the system is often only damage to buildings and systems. They monitored once consequential damage can result in extensive destruction that has occurred. can also have consequential damage. As a result, smart monitoring The damage is dependent on the systems are used more and more. power and location of the strike. But They constantly monitor the different the design of the lightning and surge functions in a system. They immediately protection concept has a bearing on the report results to a central control extent of the damage. unit. This helps the system to react Systems that are particularly at risk immediately to errors and thereby to of lightning strikes are those in exposed prevent consequential damage as well as locations or with a large surface area, long downtimes. e.g., wind turbine generators, power plants, industrial operations covering a large area, and rail systems. In such systems, complete lightning protection is generally very difficult, or even impossible, to implement. Damage or

Fig. 32: The lightning monitoring system

26 PHOENIX CONTACT The basics of surge protection | The lightning monitoring system

5.2 Lightning current detection

The LM-S lightning monitoring system If lightning strikes are measured in wind (Fig. 32) has the option of lightning turbines or buildings, conclusions can current detection: if a strike hits the be drawn at any time from the relation lightning interception rod, a magnetic between the lightning parameters and field is created around the protective the destruction associated with this. device that carries the lightning current. Furthermore, the evaluation enables The LM-S uses the Faraday effect to conclusions to be drawn about the measure this current. As such, the light efficiency of the lightning protection is polarized in the measuring path of system. the sensor. The magnetic field resulting Lightning information systems are from the lightning strike makes the also used to collect information on previously polarized light measurable lightning strikes for claims settlement. (Fig. 33). The system transmits the These systems can locate a lightning light signal from the sensor via fiber strike with a precision of up to 200 m. optics to the evaluation unit. The Whether and at what point the lightning characteristics of the lightning events – strikes a building or system can only be maximum amplitude, lightning current determined with a lightning monitoring slope, specific energy, and charge – are system – such as the LM-S. detected and stored along with the date Fig. 33: Operating principle, Faraday effect and time of the lightning strike.

LM-S lightning monitoring system The lightning monitoring system detects lightning strikes in the lightning protection system of a building or system. All measured data can be accessed remotely via various interfaces such as the integrated web interface or Modbus. The measured variables of the pulse current are: • Amplitude Ipeak • Gradient di/dt • Load Q • Specific energy W/R

Fig. 34: Burj Khalifa, LM-S application

PHOENIX CONTACT 27 The basicsofsurgeprotection |Areas ofapplication be derived from this(Fig. 35). devices, IEC product standard for surgeprotective individual SPDtypesare defined inthe (refer to Table 2).Therequirements for different typesare therefore required the protection classto beachieved. zones. Theirpower values are basedon devices for alllinesthat cross between provides coordinated surgeprotective The lightningprotection zoneconcept 6.1.1 6.1 greatly. Itisworthexaminingtheseapplications incloserdetail. system prerequisites. Correspondingly, allthesolutionsorsteps involved canvary as well asphotovoltaic Ingeneral,allareas installations. have different very individual are usedinto low-voltage systems, telecommunications andsignalprocessing networks, product standardThe IEC 61643 dividesapplications where surgeprotective devices 28 6 A multi-level protection conceptcan Depending onthezonetransition, PHOENIX CONTACT Protecting AC systems SPD types and Fields of application technologies 61643- 11 [6]. Fig. 35: Multi-level protection concept protection Multi-level Fig. 35: Table 2: zoneand corresponding Lightningprotection transition SPDtype electrical system, e.g., main system, electrical overvoltage category overvoltage distribution system Feed point of the the of point Feed LPZ 0 LPZ 0 LPZ 2 LPZ 1 Zone transition SPD type 1or type SPD SPD type 2 type SPD A B

IV

SPD LPZ3 LPZ2 LPZ1 LPZ1 point of the electrical system, system, electrical the of point In the vicinity of the feed feed the of vicinity the In SPD type e.g., sub-distributions overvoltage category overvoltage Type 1 Type 3 Type 2 Type 2 SPD type 2or type SPD SPD type 3 type SPD

SPD III Lightning current arrester Surge protective device Surge protective device Device protection Designation electrical consumables overvoltage category overvoltage SPD type 2or type SPD Devices and Devices SPD type 3 type SPD

SPD II/I The basics of surge protection | Areas of application

The multi-level functionality limits the Nominal voltage of the Conductor-neutral Rated lightning protection level from zone power supply system conductor voltage surge voltage to zone. The amplitudes and specific (mains) according to derived from the total energies of the surge voltages or surge IEC 60038 nominal AC voltage Overvoltage category currents to be expected gradually or nominal DC Three- Single- voltage I II III IV decrease. The voltage value to which phase phase the individual SPDs must limit the V V V VVVV surge voltages also decreases. This is achieved by correspondingly low voltage 50 330 500 800 1500 protection levels: their upper limits 100 500 800 1500 2500 are based on the dielectric strength 120 – 240 150 800 1500 2500 4000 of the equipment to be protected in 230/400 300 1500 2500 4000 6000 the immediate vicinity. The dielectric 277/480 strength is specified according to 400/690 600 2500 4000 6000 8000 IEC 60664-1 [9] in the overvoltage categories I to IV (Table 3). 1000 1000 4000 6000 8000 12,000 Table 3: Overvoltage categories based on the nominal voltage 6.1.2 Type 1: lightning current arrester lower the energy input to be managed. Type 1 surge protective devices must With regard to the abrupt change of fulfil the highest requirements in terms impedance, and therefore also the of amplitude and specific energy from voltage difference across the spark gap, surge voltages or surge currents, as they the non-linear characteristic is referred are supposed to protect from direct to as voltage-switching. A significant lightning strikes. In the typical installation advantage that arises from the low environment of the main distribution, residual voltage is the low load on the Fig. 36: Equivalent circuit of an enclosed spark the demand placed on the short-circuit equipment to be protected as a result gap withstand capability is often very high. of voltages above the specified nominal In order to be able to meet these voltage or maximum continuous voltage. requirements, powerful technology is For the comparatively long duration of the dielectric strength of the air alone. required, e.g., spark gap technology. lightning currents, the residual voltage Even if the installation environment of a spark gap is very low, in the range of type 1 SPDs does not generally Spark gap technology of the maximum continuous voltage require it, the voltage protection level The operating principle of a spark gap of the device to be protected. Type 1 of modern, triggered spark gaps is often is initially very simple: two electrodes SPDs with voltage-limiting components at the level of the lowest overvoltage are placed at a specific distance from are often several hundred volts over category I (based on the nominal voltage each other and create an insulating state this – a significantly greater load for the of the system). (Fig. 36). If there is a voltage present protected equipment. between the two electrodes that causes Modern spark gaps are generally the dielectric strength of the air (approx. encapsulated in robust, enclosed steel 3 kV/mm) in this space to exceed the housings, so that during the discharge surge voltage, then an electric arc is process, no ionized gases generated formed. In comparison to the insulating by the electric arc can escape into the state with an impedance in the giga-ohm environment. Furthermore, spark gaps range, the impedance of the electric arc are often triggered: is extremely low and so, therefore, is the They have additional wiring to support voltage drop across the spark gap. the through-ignition of the spark gap. This characteristic is ideal for This limits the voltage protection level discharging lightning currents: the lower to a very low level – significantly lower the residual voltage of the spark gap, the than the voltage that results based on

PHOENIX CONTACT 29 The basics of surge protection | Areas of application

Sequential current extinguishing capacity Spark gap technology without 20 kA A special characteristic for spark gaps 2000 V (8/20 µs) line follow current is the sequential current extinguishing 1500 V 15 kA For maximum system availability, capacity, Ifi. If a spark gap is ignited by limiting the line follow currents is 1000 V 10 kA means of a surge voltage, it represents essential: a kind of short circuit that drives 500 V 5 kA • Upstream overcurrent the current for the connected mains protective devices do not trip 0 V 0 kA network. The spark gap must therefore • The installation is not loaded by be in the position to interrupt the mains high current flows 0 µs 10 µs 20 µs current of its own accord, after the • The service life of the spark gap discharge process, without triggering the Fig. 37: Typical residual voltage curve of a is increased upstream overcurrent protective device. triggered spark gap when loaded with a For the first time, Phoenix Contact The sequential current extinguishing (8/20 μs) pulse has been able to develop and capacity indicates up to which offer a spark gap on the market prospective short-circuit current this is that is completely free of line guaranteed at the installation location. energy input as low as possible and follow currents, featuring Safe Modern spark gaps must be able to do increase the robustness. In the case Energy Control technology two things: of sequential currents, however, the (refer to 6.1.10). • Discharge large amounts of energy impedance must be as high as possible in from brief lightning currents order to ensure fast elimination. • Independently eliminate sequential In order to withstand high lightning currents from powerful supply current amplitudes of up to 50 kA networks on supply networks with possible short- circuit currents up to 100 kA, In the case of lightning currents, in the today's spark gaps are therefore often best case, the impedance of the spark complex constructions and consist of gap is very low, in order to keep the many individual functional parts (Fig. 38).

Insulation caps, resistant to high High-performance copper temperatures and pressure wolfram electrodes

Enclosed Electric-arc-cooling steel housing insulating parts

Fig. 38: Individual components of a modern, enclosed spark gap

30 PHOENIX CONTACT The basics of surge protection | Areas of application

6.1.3 Type 2: surge protective varistors as type 1 SPDs for Lightning device Protection Level I. Despite this, this concept has serious shortcomings: Type 2 surge protective devices are if the characteristics of the varistors generally installed in sub-distributions or connected in parallel do not match machine control cabinets. These SPDs precisely, a requirement that is very must be able to discharge induced surge hard to meet, the individual paths are voltages from indirect lightning strikes placed under differing loads during the Fig. 39: Equivalent circuit diagram of a varistor or switching operations but not handle procedure. Correspondingly, they age direct lightning strikes. As such, the very differently. Over time, the uneven energy input is significantly reduced. In loads become ever greater. This finally any case, induced surge voltages caused leads to varistor overload. by switching operations are often very dynamic. Here, a discharge technology with fast response behavior stands up to the test, e.g., varistor technology.

Varistor technology Varistors (variable resistor or V metal oxide varistor, MOV) (Fig. 39) are 2000 semiconductor components made from 1000 metal oxide ceramics. They exhibit a non-linear current-voltage characteristic 800 curve (Fig. 40). In low voltage ranges, 600 the impedance of a varistor is very high, however in higher voltage ranges the 400 impedance drops away rapidly, so that very high currents can be discharged 200 without any problems. 100 For this reason, the characteristics 10­5 10­4 10­3 10­2 10­1 10­0 101 102 103 104 A 105 of varistors are referred to as i voltage- limiting. With a typical response time in the lower nanosecond range, Fig. 40: Voltage-current characteristic curve of a varistor with 320 V AC rated voltage varistors are very well suited even to limiting particularly dynamic surge voltage phenomena.

Varistors that carry lightning current 2000 V 20 kA (8/20 µs)

High-performance varistor ceramics can 1500 V 15 kA even exhibit a pulse discharge capacity of up to 12.5 kA (10/350 μs), which 1000 V 10 kA means that they are also suitable as a type 1 SPD for environments with low 500 V 5 kA protection levels. 0 V 0 kA For a higher pulse discharge capacity of 25 kA to 50 kA (10/350 μs), generally, multiple varistors must be used in a 0 µs 10 µs 20 µs 30 µs parallel connection. Surge protection manufacturers who have no spark Fig 41: Residual voltage of a varistor with 350 V AC rated voltage under a load of 25 kA (8/20 μs) gap technology therefore often use

PHOENIX CONTACT 31 The basicsofsurgeprotection |Areas ofapplication Fig. 42: Multi-level protection concept with arange concept with SPDtypes protection ofconsecutive Multi-level Fig. 42: corresponding (supply) lines. take onthesurgeprotection for all combined devices for They thispurpose. communication lines.There are in theterminal suchasdata device, the protection ofotherinterfaces protection ofthepower supply to comparison to type2are even lower. in terms ofnominaldischargecapacity in based onvaristors, buttherequirements are mostsimilarto type2,whichare Technologically speaking,type3SPDs device. direct mountingonaPCBoftheend devices for insockets installation orfor standard DINrailmounting,there are of designs.For example:inaddition to 3 SPDsare available widerange inavery environments,differing installation type terminal device to beprotected. Dueto rightinfrontgenerally installed ofthe Type 3surgeprotective devices are Type 3:device protection 6.1.4 32 Often itissensibleto linkthe PHOENIX CONTACT Type 2/3 Type 2 Type 1 HV

SPD

SPD SPD UV 1 to thetype2SPD. SPD, whichisgreater thanorequivalent already guaranteed by aUcofthetype3 zone concept,selective addressing is expected inthisarea oftheprotection surge voltagesofalower amplitudeare not overloaded interms ofenergy. Since must beensured thattype3SPDsare type 2SPDare to becoordinated. It zones, atype3SPDandanupstream be derived from this(Fig.42). devices, IEC 61643-11 [6]. product standard for surgeprotective individual SPDtypesare defined inthe (refer to Table 2).Therequirements for different typesare therefore required the protection classto beachieved. zones. Theirpower valuesare basedon devices for alllinesthatcross between provides coordinated surgeprotective The lightningprotection zoneconcept 6.1.5 Coordinating Starting from theinternalStarting protection A multi-level protection conceptcan Depending onthezonetransition, different SPD types

SPD SPD UV 2 almost completely transitioned. current ensures thecurrent flowis most ofthedurationlightning of justafew hundred volts throughout Their comparatively low residual voltage provide aclearadvantageinthisarea. Type 1SPDsbasedonsparkgaps general conditionsfor coordination. SPDs are different, very there are no could beoverloaded. thetype2SPDs otherwise important addressing oftheSPDsisparticularly be borne by type1SPDs,selective be considered here, whichcanonly strikes lightningstrikes orpartial must As thepossibilityofdirect lightning 1 SPDsmustbeensured. onceagain between type2SPDsandupstream type protection zones,thecoordination

SPD SPD UV As thetechnologies usedfor type1 In thedirection oftheexternal 3 The basics of surge protection | Areas of application

6.1.6 Grid systems according to IT system IEC 60364 In this grid system, the neutral point of L1 the transformer supplying the energy L2 The design of a surge protection is not grounded, or only grounded L3 concept for AC systems depends, among via a high impedance. The parts of N other things, on the existing grid system. the electrical system are connected PE These systems can vary depending to a local grounding system that is on the design of the grounding of the separated from the grounded point of transformer providing the supply, the the transformer. If a neutral conductor consumer system, and their connection is also routed from the neutral point of Fig. 43: TN-S system to one another. the transformer supplying the energy, The directive for erecting low-voltage this is routed separately from the local power supply systems, IEC 60364-1 [10] protective conductor. A three-phase lists the following system configurations: power supply consists of four or five conductors: L1, L2, L3, if appropriate, L1 TN-S system N, and local PE (Fig. 46). L2 In this grid system, one point – usually One peculiarity of the IT system is L3 the neutral point – of the transformer that an insulation fault to ground may PEN supplying the energy is usually directly occur for a limited period of time. The grounded. The neutral conductor (N) ground fault in the phase must merely and protective conductor (PE) are be detected by insulation monitoring routed to the consumer system in and reported, so that it can be promptly separate conductors. A three-phase rectified. Only in the event of a second Fig. 44: TN-C system power supply consists of five conductors: ground fault would this lead to a short L1, L2, L3, N, and PE (Fig. 43). circuit between two phases and the relevant surge protection equipment TN-C system would trip. Surge protective devices L1 In this grid system, the neutral point of for use in IT systems must therefore L2 the transformer supplying the energy be able to withstand the phase-to- L3 is directly grounded. The neutral phase voltage of the system as well as N conductor and protective conductor are the tolerance. This is ensured by the PE routed to the consumer system in one normative requirement that only SPDs conductor (PEN). A three-phase power with a maximum continuous voltage of supply consists of four conductors: L1, at least the phase-to-phase voltage plus L2, L3, and PEN (Fig. 44). tolerance may be used between the phase and PE in IT systems. Fig. 45: TT system TT system In this grid system, the grounded point of the transformer is routed to the system solely as a neutral conductor. L1 The parts of the electrical system are L2 connected to a local grounding system L3 that is separated from the grounded point of the transformer. The neutral PE conductor and the local protective conductor are routed to the consumer system in separate conductors. A three- phase power supply consists of five conductors: L1, L2, L3, N, and local Fig. 46: IT system PE (Fig. 45).

PHOENIX CONTACT 33 The basics of surge protection | Areas of application

6.1.7 American grid systems system first of all. A three-phase L1 L2 L3 N power supply consists of four or five Other grid systems are used, especially conductors: L1, L2, L3, if appropriate,

in the Northern and Central American N, and GND (Fig. 48). SPD SPD SPD SPD regions. The most important are: • Wye system Split-phase system • Delta system This widely used two-phase system • Split-phase system is grounded by means of a center tap between the two phases and a neutral Wye system conductor is routed from there. A PE These systems correspond to the two- phase power supply consists of TN systems; the neutral point of four conductors: L1, L2, N, and GND Fig. 50: CT1 connection scheme or 4+0 circuit the supplying transformer is directly (Fig. 49). grounded and from there, the protective conductor (grounding conductor, GND) 6.1.8 Connection scheme is routed to the consumer system. L1 L2 L3 N Insulated wye systems do also exist, but Surge protective devices are part of the there are comparably few. A possible equipotential bonding of a structural

neutral conductor is generally first of system. In the event of a surge voltage, SPD SPD SPD all tapped within the consumer system. they connect the active conductor This then corresponds to a TN-C-S in electrical installations with the system. A three-phase power supply grounding.

consists of four or five conductors: Depending on the grid system of the SPD L1, L2, L3, if appropriate, N, and GND consumer system, different SPDs can (Fig. 47). be used. They are combined in various PE connection schemes (CT), to establish Delta system this connection. In the installation Fig. 51: CT2 connection scheme or 3+1 circuit These systems have no direct equivalent directive for surge protection, according to IEC. Grounding either takes IEC 60364-5-53 [11], the following types place via one of the phases (corner- are specified: grounded) or via a center tap between • CT1 connection scheme: a number of active conductors (Fig. 50). two phases (high-leg). The GND is combination of SPDs that have a • CT2 connection scheme: a routed from the respective grounding mode of protection between each combination of SPDs that have point to the consumer system. Insulated active conductor (outer conductor a mode of protection between delta systems do also exist, but there and neutral conductor, if present) each outer conductor and neutral are comparably few. and PE conductor. This connection conductor and a mode of protection The neutral conductor is, if required, scheme is often designated as a x+0 between the neutral conductor and also usually tapped within the consumer circuit, whereby x represents the the PE conductor. This connection

L1 L1 L1 N L2 N L2 L3 L2 L3 N GND GND GND

Fig. 47: Wye system Fig. 48: High-leg and corner-grounded delta Fig. 49: Split-phase system system

34 PHOENIX CONTACT listed inTable 4. scheme intheindividualgridsystems are The possibleusesofthisconnection Table 4: schemes systems and grid Connection The basicsofsurgeprotection |Areas ofapplication IT system withrouted neutral the SPD installation location the SPDinstallation number ofouter conductors (Fig.51). circuit, whereby xrepresents the scheme isoftendesignated asax+1 Noleakagecurrent to the • Lower voltage protection level • Canbeuseduniversally inall • type are: The advantagesofthisconnection scheme for TNandTTsystems. SPDs withtheCT2connection mainly providesPhoenix Contact CT2 connection scheme IT system withoutrouted conductor the neutral andprotective the useofsparkgapsbetween protective conductor dueto conductor between outer andneutral countries worldwide neutral conductor Grid system at TN system TT system conductor residual current protective Only downstream of a device CT1 possible. cables) canbeminimizedasmuch as and voltagedrop over theconnecting the voltageprotection level oftheSPDs the overall protection level (consistingof length cisofrelevance. Assuch,even easytoparticularly ensure, ashere only InthecaseofV-wiring,0.5 m. thisis mustlengths a,b,notexceed andc, ofthecable In bothcases,thetotal V-wiring (V-shaped wiring), refer to • refer to Branchwiring(stub wiring), • two different ways: possible bendingradii. aspossiblewiththelargest as short SPD connectingcablesare always laid to beprotected. Withthisinmind,the protection inparallelto theequipment whenconnectingsurge particularly can weaken theprotective effect, voltage drop intheconnectingcables electrical conductors. Thisadditional inductive voltagedrop canresult onthe If transientovervoltages occur, an Connection and 6.1.9 Fig. 53 Fig. 52 SPDs canessentially beconnected in Connection scheme of overcurrent protection SPDs CT2 NA upstream overcurrent protective device be usedupto anominalvalueofthe capability.withstand does notexceed itsshort-circuit current location ontheSPDinstallation provided theprospective short-circuit with nominalcurrents ofany strength, This wiringenablesuseinsystems F2,withalowerdevice, nominalvalue. second additional overcurrent protective overcurrent protective witha device, the nominalvalueofF1upstream can ormust beprotected dependingon Fig. 52:Branch wiring Fig. 53: V-wiringFig. 53: The V-wiring, however, canonly In thecaseofbranchwiring,SPD b PHOENIX CONTACT SPD SPD c a c

35 The basics of surge protection | Areas of application

F1 or a nominal current of the system protective conductor for type 1 upstream overcurrent protective that does not exceed the continuous SPDs: min. 16 mm2 devices. current capacity of the connecting cables – Connection cross section of the • The final overcurrent protective and the connection terminal blocks of main grounding busbar or the device before the SPD must not the SPD. protective conductor for type 2 exceed the maximum nominal As part of the electrical installation, SPDs: min. 6 mm2 value of the upstream overcurrent corresponding legal or regulatory • Over a specific nominal value of the protective device as specified by the requirements are to be fulfilled for the upstream overcurrent protection, the SPD manufacturer. connection and overcurrent protection minimum cross section is determined • The upstream overcurrent protective of surge protective devices that by the connecting cables' need for device should, as far as possible, be principally aim to ensure the operational short-circuit withstand capability able to bear the required amplitudes reliability of the system. Furthermore, • If the SPD connecting cables of lightning and surge currents, for correct functioning of the surge carry operating current, then the depending on the Lightning Protection protection, specific conditions are to continuous current load can be used Level. In particular with regard be taken into account with regard to to determine the minimum cross to high-energy lightning currents, connection and fuse protection. section as of a certain current value under- dimensioned fuses can pose The requirements are based on a risk, as they can be destroyed in a various parts of IEC 60364 for creating Overcurrent protection very short time due to high-energy low-voltage systems: on the one When designing the overcurrent inputs. hand, Part 5, Section 53, Main Section protection of SPDs, the various elements Adhering to the selectivity is therefore 534 [11], regarding the selection and must first be prioritized: the top priority. In the simple case setup of surge protective devices, and • Priority of the system supply: that the two overcurrent protective on the other, Part 4, Section 43 [12], Branch wiring with separate F2 devices to be taken into account are gG regarding protective measures against overcurrent protective device in the fuses, then a nominal value of 1250 A overcurrent, as well as the product branch applies, which must be F2 × 1.6 ≤ F1. standard for surge protective devices, • Priority of the system surge If one or both of the overcurrent IEC 61643-11 [6]. protection: V-wiring or branch wiring protective devices is a circuit breaker, without separate F2 overcurrent then their tripping characteristics must Connection cross sections protective device be compared with each other or with If these requirements are combined, this In the first case, the separate F2 the fuse characteristics and, if applicable, results in the following conditions for overcurrent protection equipment tailored to each other, so that the dimensioning the connecting cables of ensures that in the event of the failure curves are not affected (Fig. 54 and 55). SPDs (based on PVC-insulated copper of the SPD (e.g., a short circuit), the F1 In areas with short-circuit currents, cables): upstream overcurrent protective device they must have a sufficient time interval, • The minimum cross sections for does not trigger and that the supply to so that the respective downstream the SPD connecting cables first of the equipment to be protected is not overcurrent protective device can all result from the requirements for interrupted. In this case, however, the address the other and switch off. installing surge protective devices, equipment is no longer protected from A similar scenario applies in the depending on the active conductor subsequent overvoltage events. event that a circuit breaker should connection or the main grounding In the second case, the F1 upstream represent the overcurrent protection busbar/the protective conductor overcurrent protective device takes on for the SPD as F1, without a separate (PE(N)) as well as the type of the the overcurrent protection in the event F2 overcurrent protective device. SPD: that the SPD fails. The failure of the Then, the switching- off characteristics – Connection cross section of the supply is hereby accepted, so that no of the switch must be compared with active conductor for type 1 SPDs: damage can be caused by subsequent the characteristics of the maximum min. 6 mm2 overvoltage events. overcurrent protection specified for – Connection cross section of the When dimensioning the overcurrent the SPD by the manufacturer. This active conductor for type 2 SPDs: protection, the following points should must not be exceeded in the range for min. 2.5 mm2 be kept in mind: short- circuit currents. – Connection cross section of the • Selectivity of the respective main grounding busbar or the overcurrent protective device to

36 PHOENIX CONTACT The basics of surge protection | Areas of application

Circuit Fuse breaker 1 h Circuit breaker 1 h Fuse Trigger Trigger time 10 min time 10 min

1 min 1 min

10 s 10 s

1 s 1 s

100 ms 100 ms

10 ms 10 ms

1 ms 1 ms 1 ms 1 k 10 k 100 k 100 1 k 10 k 100 k

Current (A) Current (A)

Fig. 54: Switching-off characteristics of a circuit breaker (F1) and a selective Fig. 55: Switching-off characteristics of a circuit breaker (F1) that is suitable gG fuse (F2) as an upstream overcurrent protective device for an SPD with a maximum backup fuse of 315 A gG

SPDs with integrated overcurrent level protection concepts to be easily protection implemented: protection concepts with Products that already contain Safe Energy Control technology (SEC) corresponding fuses, such as the combine maximum performance with FLASHTRAB SEC HYBRID, represent a a long service life, so that electrical particularly straightforward solution for fittings are always safely protected and overcurrent protection of SPDs. maintenance costs are reduced. Installing SPDs with SEC technology is easy, cost- 6.1.10 Safe Energy Control effective, and space-saving. The individual technology (SEC) SPD types can be found in the product ranges as shown in Table 5. Phoenix Contact provides SPDs which are perfectly matched with other items from the range and that allow multi-

FLASHTRAB SEC HYBRID SPD type Product range Thanks to the integrated fuse, no external protection elements are Type 1 FLASHTRAB SEC required, and space and costs are reduced. The protective effect is Type 2 VALVETRAB SEC increased, as the voltage difference resulting from the fuse is already Type 3 PLUGTRAB SEC contained in the voltage protection level of the SPD. The short Table 5: Product ranges with connecting cables required for Safe Energy Control technology SPDs are easy to set up (Fig. 56). Fig. 56: FLT-SEC-H-T1-1C-264/25-FM

PHOENIX CONTACT 37

38 38 PHOENIX CONTACT PHOENIX

directly coordinated combination of of combination coordinated directly Fig. 57: Multi-level protection concept based on the example of an industrial production system production industrial an of example the on based concept protection Multi-level Fig. 57:

the FLASHTRAB SEC T1+T2, the only only the FLASHTRAB SEC T1+T2, the

the narrowest type 2 SPD, and with with and SPD, 2 type narrowest the

T1

voltage, with the VALVETRAB SEC VALVETRAB SEC the with voltage,

type 1 spark gap for this nominal nominal this for gap spark 1 type N PENPE

the SEC range offers the most compact compact most the offers range SEC the

T1-350/25-P T1-350/25-P T1-350/25-P T1-350/25-P SEC PLUS 440, FLASHTRAB the With

P -SEC- T FL P P -SEC- -SEC- T T FL FL P -SEC- T FL

T1 T1 T1 T1

B HTRA AS FL B HTRA AS FL B HTRA AS FL

design

Compact and consistent pluggable pluggable consistent and Compact

surge-proof fuses. surge-proof

which is also thanks to the integrated integrated the to thanks also is which

wiring without any kind of backup fuse, fuse, backup of kind any without wiring

product range can be operated in branch branch in operated be can range product

type 3 SPDs from the PLUGTRAB SEC SEC PLUGTRAB the from SPDs 3 type

T2 T3

as the FLASHTRAB SEC HYBRID. The The HYBRID. SEC FLASHTRAB the as

with integrated surge-proof fuse, such such fuse, surge-proof integrated with

beyond this scope, products are available available are products scope, this beyond

T3-230-P T2-350-P T2-350-P T2-350-P N/PE-350-P

PLT-SEC C -SE L VA C -SE L VA C -SE L VA T2 -SEC- L VA

T3 T2 T2 T2 N/PE

PLUGTRAB applications For protection. overcurrent B ETRA LV VA B ETRA LV VA B ETRA LV VA B ETRA LV VA

12 11

ratings of 315 A gG without separate separate without gG A 315 of ratings

type 2 SPDs can be used for main fuse fuse main for used be can SPDs 2 type

installation is the top priority, type 1 and and 1 type priority, top the is installation

For applications where protecting the the protecting where applications For

backup fuse for all common applications. applications. common all for fuse backup

a solution without separate arrester arrester separate without solution a

Energy Control technology provide provide technology Control Energy implemented with separately laid laid separately with implemented and selected, be to type connection the

supply. Depending on the grid system, system, grid the on Depending supply. Safe with devices protective surge and that the remaining installation is is installation remaining the that

in the area of the low-voltage main main low-voltage the of area the in arresters current lightning powerful The system in the main distribution, so so distribution, main the in system

where the supply lines enter the building building the enter lines supply the where already converted into a TN-S TN-S a into converted already

application

FLASHTRAB product range at the point point the at range product FLASHTRAB assumed in this example, is generally generally is example, this in assumed

Backup-fuse-free solution for every every for solution Backup-fuse-free

is provided by a type 1 SPD from the the from SPD 1 type a by provided is A supply as a TN-C system, as as system, TN-C a as supply A

A 1 1 0 transition zone protective The triggered. not is upstream VALVETRAB SEC product range. range. product VALVETRAB SEC

guaranteed because the fuse protection protection fuse the because guaranteed thanks to a type 2 SPD from the the from SPD 2 type a to thanks

system

process. Maximum system availability is is availability system Maximum process. 2, 2, 1 by provided is transition zone

external lightning protection protection lightning external

under minimal load by the discharge discharge the by load minimal under halls and office rooms, the protective protective the rooms, office and halls

Industrial production system with with system production Industrial

supply, including the SPD, are placed placed are SPD, the including supply, the production system, for machine machine for system, production the

are ideally tailored to one another. one to tailored ideally are entire the but equipment, protected the In the further sub-distributions of of sub-distributions further the In

protection level, and discharge current, current, discharge and level, protection only not that means This installation. the main distribution. main the

maximum continuous voltage, voltage voltage voltage, continuous maximum entire the benefits currents follow many advantages when used directly in in directly used when advantages many

installations. Parameters such as the the as such Parameters installations. line of avoidance The current. follow type 2 SPD on a varistor basis provides provides basis varistor a on SPD 2 type

very easily put together for standard standard for together put easily very line no with technology gap spark type 1 SPD on a spark-gap basis and a a and basis spark-gap a on SPD 1 type

multi-level protection concepts can be be can concepts protection multi-level feature to first the are arresters directly coordinated combination of a a of combination coordinated directly

Thanks to the SPDs from the SEC range, range, SEC the from SPDs the to Thanks current lightning technology SEC The (Fig. 59) can also be used here. This This here. used be also can 59) (Fig.

overcurrent protection to trigger. trigger. to protection overcurrent combination of FLASHTRAB SEC T1+T2 T1+T2 FLASHTRAB SEC of combination

concepts currents that can lead the upstream upstream the lead can that currents Alternatively, the protective device device protective the Alternatively,

6.1.11 Multi-level protection protection Multi-level installation with high line follow follow line high with installation (Fig. 58). (Fig. 58).

type 1 line follow currents load the the load currents follow line 1 type FLT-SEC-P-T1-3C-350/25-FM is ideal ideal is FLT-SEC-P-T1-3C-350/25-FM

making maintenance a great deal easier. deal great a maintenance making Conventional arrester. current 230/400 V AC TN-C system, the the system, TN-C AC 230/400 V

in the SEC portfolio are pluggable, pluggable, are portfolio SEC the in lightning 1 type powerful a requires If, for example, it is a three- phase phase three- a is it example, for If,

arrester in a confined space. All products products All space. confined a in arrester concept protection surge consistent A various SPD types and circuit versions. versions. circuit and types SPD various

type 1 spark gap and type 2 varistor varistor 2 type and gap spark 1 type the voltage level of the supply, there are are there supply, the of level voltage the

Impact-free and durable and Impact-free The basics of surge protection | Areas of application of Areas | protection surge of basics The The basics of surge protection | Areas of application

neutral and protective conductors. voltage, the PLT-SEC-T3-230-FM can The VAL- SEC- T2-3S-350-FM is then then be used (Fig. 61). offered as a type 2 SPD (Fig. 60). In the machine control cabinets and in offices, the 2 3 protective zone transition is provided by means of type 3 SPDs from the PLUGTRAB SEC range, directly upstream of sensitive end devices. For an end device operated with 230 V nominal

FLASHTRAB SEC The type 1 SPDs from the availability, as upstream overcurrent FLASHTRAB SEC family all use protection systems are not triggered the spark gap technology that is as part of the discharge process. free of line follow currents. They thereby guarantee maximum system Fig. 58: FLT-SEC-P-T1-3C-350/25-FM

FLASHTRAB SEC T1+T2 The unique SPD combination on the • Varistor arrester to limit dynamic market, FLASHTRAB SEC T1+T2, surge voltages optimally protects sensitive equipment • Optimum energy distribution by means of: between the protective levels • Powerful spark gap to discharge direct lightning currents Fig 59: FLT-SEC-T1+T2-3C-350/25-FM

VALVETRAB SEC The VALVETRAB SEC T2 impresses up to 315 A gG. It is also possible to above all due to the powerful, internal operate it at the location installation thermal disconnect device, in addition with prospective short-circuit to the narrow design – just 12 mm currents up to 50 kA. per pole. The SPD can therefore be used without a further backup fuse Fig. 60: VAL-SEC-T2-3S-350-FM

PLUGTRAB SEC The PLUGTRAB SEC T3 has enables connection in branch wiring integrated surge-current resistant without separate backup fuse, fuses. As such, it can be used with irrespective of the nominal current end devices operated with both and the protection of the circuit. alternating current and direct current. The integrated overcurrent protection Fig. 61: PLT-SEC-T3-230-FM

PHOENIX CONTACT 39 • Battery sets Battery • Chargingpower supply units • Regulated power supply units • Controlled andnon-controlled • characteristics are: power supply systems withlinearsource Typical power sources ofdirect current Railvehicles • Computer centers • storage inUPSsystems Battery • Mobileloads,fork-lift trucksor e.g, • Loads with low direct current power • mainly usedfor: with linearsource characteristics are short-circuit currents. applies to systems withlimited orlow respective systems. Thisparticularly without precise knowledge ofthe easily selectsurgeprotective devices to another. Itistherefore impossibleto characteristics greatly canvary from one direct current systems withlinearsource The operatingbehavior ofdifferent 6.2 the groundingthe point for grounded 1+0circuit TNsystems at Fig. 62: The basicsofsurgeprotection |Areas ofapplication 40 systems controllers ortelecommunication supply, programmable e.g., logic Direct current power supply systems rectifiers withorwithoutsmoothing onboard power systems PHOENIX CONTACT Protection of DCsystemswithlinear voltage sources L+ L PE - F1

SPD F2 Fig. 63: 2+0 circuit for ITsystems 2+0circuit Fig. 63: overcurrent protective devices inDC selection ofSPDsandcorresponding safety requirements. site are detected, inorder to meetbasic circuit currents attheSPDinstallation that even minimalprospective short- currents, however, important itisvery with limited orlow short-circuit milliseconds. InthecaseofDCsystems protective devices inafew to trigger enough to causeupstream overcurrent minimum short-circuit current ishigh DC systems. appliesparticularly to battery-operated different operatingbehaviors. This are oftenmultiple power sources with source; for DCsystems, however, there systems, there is often only onepower power supply systems. complex thanfor alternating current systems isgenerally significantly more Selecting SPDsfor direct current Selecting surgeprotective devices systems are: L+ L PE Significant designcriteria for the In themajorityofAC systems, the In the case ofAC power supply - F1 F1 F2

SPD

SPD F2 that are farthat fromgrounding away the point for grounded 2+0circuit TNsystems Fig. 64: the system's grounding point(Fig. 64). location oftheSPDsisfaraway from grounded TNsystems iftheinstallation designed withoneortwo poles. type (refer to Fig.50)andare either systems conform to theCT1connection The preferred circuits for SPDsinDC and non-grounded DCsystems Protective circuits for grounded Maximum andminimum prospective • Number, andoperatingbehavior type, • NominalvoltageoftheDCpower • L+ L PE A 2+0circuit isalsorequired for location installation short-circuit current attheSPD of theDCpower source(s) source(s) - F1 F2

SPD

SPD F2 The basics of surge protection | Areas of application

6.3 Protection of photovoltaic systems

The increasing number and variety typical behavior of the photovoltaic The combination of switching and of versions of photovoltaic systems system are carried out. This is because, limiting components in series and parallel presents a new challenge in terms of under almost all operating conditions, arrangements is also taken into account. safety and reliability. This applies to all the panels of a photovoltaic generator Table 6 provides the required values for photovoltaic systems, such as rooftop provide an almost constant current that the discharge capacity of voltage-limiting systems on single-family dwellings, off- is at the same time close to the short- and combined SPDs that are switched in grid systems or free-standing systems. circuit current of the system. series in structural systems. Photovoltaic systems are often Voltage-limiting components or subjected to tough weather conditions, CLC/TS 50539-12 installation combined SPDs can thereby function as such as the effects of lightning, due to directive varistors or varistors and gas-filled surge their exposed location. In order for In addition to the product standard, protective devices in series connection the systems to be able to continue to there is also the CLC/TS 50539-12 [13] (Fig. 65). operate safely and profitably, installing installation directive. This provides lightning and surge protection is key information for the installation of recommended. Thanks to special photovoltaic systems in the field. The standards and installation directives, it directive differentiates between free- is possible to optimally plan and install standing systems and structural systems photovoltaic systems. (rooftop systems). In the installation directive, there is a IEC 61643-31 – requirements and differentiation between voltage-switching test methods for surge protective and voltage-limiting components. devices in photovoltaic systems Thanks to the IEC 61643-31 [8] product standard, it is possible to qualify lightning and surge protective devices according to their operating behavior and thereby guarantee the quality and safety of these products. The standard describes testing procedures for SPDs for use in photovoltaic systems and takes into account the peculiarities of the DC MOV MOV + GDT in series voltage and its properties. Among other things, special tests that replicate the Fig. 65: Examples of voltage-limiting components or combined SPDs in series connection

Number of external protective devices Maximum LPL Current 2≥4

(10/350) Per prot. mode Itotal Per prot. mode Itotal

I8/20 I10/350 I8/20 I10/350 I8/20 I10/350 I8/20 I10/350 I or unknown 200 kA 17 kA 10 kA 34 kA 20 kA 10 kA 5 kA 20 kA 10 kA II 150 kA 12.5 kA 7.5 kA 25 kA 15 kA 7.5 kA 3.75 kA 15 kA 7.5 kA III or IV 100 kA 8.5 kA 5 kA 17 kA 10 kA 5 kA 2.5 kA 10 kA 5 kA

Table 6: Values for I10/350 and I8/20 for voltage-limiting and combined SPDs (voltage-switching and limiting components in series)

PHOENIX CONTACT 41 The basics of surge protection | Areas of application

Number of external protective devices Maximum LPL Current 2≥4 (10/350) Per prot. mode Per prot. mode Itotal Itotal I10/350 I10/350

I or unknown 200 kA 25 kA 50 kA 12.5 kA 25 kA

II 150 kA 18.5 kA 37.5 kA 9 kA 18 kA

III or IV 100 kA 12.5 kA 25 kA 6.25 kA 12.5 kA

Table 7: Values for I10/350 and I8/20 for voltage-switching and combined SPDs (voltage-switching and limiting components in parallel)

If voltage-switching SPDs or components are used in parallel to voltage-limiting components, then the surge current will be divided very unevenly. For this reason, other values are to be used (refer to Table 7). Voltage-limiting components or Parallel MOVs MOV + GDT parallel combined SPDs can function as varistors or varistors and gas-filled surge Fig. 66: Examples of voltage-limiting components or combined SPDs in parallel connection protective devices in parallel connection (Fig. 66).

+/­ +/­ Advantages of the Y-circuit Phoenix Contact provides all surge voltages, voltage-limiting components protective devices for photovoltaic offer the advantage of a low voltage applications based on voltage- limiting protection level compared with components in series. The circuit voltage-switching components. consists of three varistors in a so-called Y-circuit. In the event of failure, e.g., the short circuit of a varistor, a second varistor connected in series ensures that the current flow can be safely interrupted. In addition to a fast reaction time to surge

PE

Fig. 67: Y-circuit consisting of three varistors

42 PHOENIX CONTACT The basics of surge protection | Areas of application

Choosing protective devices Furthermore, CLC/TS 50539-12 exceed a length of 10 meters on the DC To select a suitable lightning and describes the installation of SPDs side and on the AC side between the surge protective device, the following depending on the line lengths between inverter and the equipotential bonding information is required: the devices to be protected and the point, then a type 1 SPD is required. • The Lightning Protection Level to be equipotential bonding point. applied Depending on whether an external • The number of external protective lightning protection system is available or devices on the building not, the required protective components The majority of photovoltaic installations should be selected on the AC side. If the are designed for Lightning Protection building or the free-standing system has Levels III or IV. In the event that the no external lightning protection system, risk analysis of the photovoltaic system then the inverter or string combiner in question results in a higher Lightning box should be protected with a type Protection Level, the lightning and 2 SPD. Provided the lines between the surge protective devices should be photovoltaic panels and the inverter chosen with a higher discharge capacity. exceed a length of more than 10 meters From experience, the majority of new on the DC side, a coupled surge voltage constructions or existing buildings that can lead to the dielectric strength of the are more than 10 meters wide are photovoltaic panel being exceeded due equipped with at least four protective to oscillation effects, thereby leading to devices. Corresponding values for the damage of the panel. In this case, placing minimum requirements for lightning and another type 2 SPD directly on the panel surge protective devices can be taken is recommended. However, if an external from Tables 6 and 7. lightning protection system is available, For free-standing systems, Table then a type 1 SPD should be installed 8 applies, which covers Lightning on the building entry or in the string Protection Levels III and IV. This table combiner box and a type 2 SPD should once again differentiates between be installed on the AC side, upstream switching and limiting components in of the inverter. If the lines between the series and parallel. photovoltaic panels and the inverter

SPDs, connected on the DC side Iimp in kA (10/350), In in kA (8/20)

limiting or combined SPDs switching and combined SPDs Maximum (voltage-switching and limiting (voltage-switching and limiting LPL Current components in series) components in parallel) (10/350)

I10/350 I8/20 I10/350

Per Per Per mode of Itotal mode of Itotal mode of Itotal protection protection protection

III or IV 150 kA 5 kA 10 kA 15 kA 30 kA 10 kA 20 kA

Table 8: Values for I10/350 and I8/20 for SPDs to protect a photovoltaic free-standing power system with several grounding points and a meshed grounding system

PHOENIX CONTACT 43 The basics of surge protection | Areas of application

Building installation the external lightning air-terminal. units, comprehensive protection is just Across the world, many photovoltaic Connect module frames to the as important and should be taken into systems are installed; among them, separate ground potential. account at the planning stage. Here, numerous rooftop systems (Fig. 68). During installation it is important that slight surge voltages can couple in and Often when it comes to rooftop the existing system is not disturbed damage the inverter or evaluation unit. installation, it is a case of integration and that it is sufficiently protected from into the existing electrical building external influences. This relates to the Free-standing systems system. The following specifications must entire installation, from the module Today, large free-standing systems be observed here: right through to the inverter on the DC (Fig. 69) are mainly used as a source • Do not route the photovoltaic lines side and of course from the inverter of income. To reduce system costs, in parallel or close to the lightning to the main connection on the AC increasing the system availability and conductor of the external lightning side. In order to enable lightning and minimizing the failure quota is important. protection system. surge protection, photovoltaic systems To this end, all components must be • Avoid the effects of lightning on the are connected to the equipotential carefully selected and correctly installed. protective conductor by means of bonding strips in the main distribution. As such, surge protective equipment a galvanic connection in which the As a consequence of this, the lightning that has been developed according lightning surge protective devices are effects can enter via the DC and AC to the valid product standard, installed upstream of the device to be side in the non-protected state. For this IEC 61643- 31 [8] for SPDs for use in protected. reason it is crucial that the entire system photovoltaic installations, should be • Observe the separation distances is considered and devices at risk are installed. between the module frame and protected. For data and communication For the majority of constellations, a type 2 SPD that is directly installed at the DC input of the inverter is sufficient. For effective protection, the data and communication lines of the inverter must also be protected in addition to the DC and AC side.

Protective devices for systems of all types Regardless of whether it is for rooftop systems on single-family dwellings, off-grid systems or free- standing systems – for the safe operation of a photovoltaic system, a lightning and surge protection concept must be created as early as the planning stage. Phoenix Contact provides powerful SPDs for all areas of application.

Fig. 68: Rooftop system on a single-family dwelling

44 PHOENIX CONTACT The basics of surge protection | Areas of application

Fig. 69: Free-standing system with external lightning protection system

New design for system voltages up with a smaller cross section, and thereby cost- effective and efficient. However, to 1500 V DC achieve cost savings in terms of cabling. this is only possible if all the components In times in which solar subsidies are In total, the balance of system (BOS) are designed for these voltages. being drastically reduced, it is essential costs can be reduced through fewer to minimize system costs accordingly string combiner boxes and lower cabling to ensure an acceptable return. Thanks expenses. Inverter manufacturers also to an increased voltage of up to 1500 benefit from this. With a system voltage V DC, this is perfectly feasible. Due to of 1500 V, the inverter performance the associated lower string currents, in can be increased by up to 20%. This practice this means customers use lines makes the photovoltaic system more

VALVETRAB-MB-...-DC-PV To keep pace with this trend, the What's more, the new product range new surge protective devices of completely fulfils the product standard the VAL- MB product range were requirements and the installation developed for voltages up to directive for Lightning Protection 1500 V DC and with a total discharge Levels III and IV. capacity of 12.5 kA ITotal (10/350 μs).

Fig. 70: VAL-MB-T2 1500DC-PV/2+V-FM

PHOENIX CONTACT 45 The basics of surge protection | Areas of application

6.4 Protection of signal transmission circuits in MCR technology

Interference-free transmission of signals plays a central role in the field of measurement, control, and regulation technology (MCR technology). Error-free operation of building services management, manufacturing or process LPZ 1 technology necessarily demands a LPZ 2 LPZ 3 high level of availability of the signals C1 transmitted. However, these are exposed C2 SPD

D1 SPD to an increasingly active electrical SPD environment. This particularly applies to weak measured values that are delivered by sensors. If the measured values are low voltages or electric currents that must be securely transmitted, carefully conditioned or evaluated, then there is an increase in the electromagnetic and Fig. 71: Lightning protection zones and classification of protective devices for MCR and IT systems high-frequency interference they are according to IEC 61643 22 [7] exposed to. Reasons for this are: • An increasing number of electrically level, surge protective devices with is not usually separated at every zone operated components in all combined protective circuits or with transition, helping to reduce installation performance classes, especially individual components are used. These work. Multiple protection levels are motors operated via frequency are installed directly upstream of the generally combined in one MCR surge inverters and other actuators. signal inputs to be protected. The protective device. As a practical solution, • The increasing miniaturization and circuits of the surge protective devices this protective module can be installed packing density of device components. to be used are adapted to the various upstream of the device to be protected • A growing volume of wireless signal types. (e.g., controller input) communication and control equipment. Divisions within the standard • Digital systems that work with ever The requirements and assignment to higher transmission frequencies. protective zones are described in detail Insufficient attention given to the in standards IEC 61643-21 [7] and above disturbance variables, incorrect IEC 61643-22 [16]. The performance of adjustments or lack of planning can protective modules for MCR technology all affect interference-free signal is described by IEC categories D1, C2, transmission. and C1. (Fig. 71) Zone transition 0A 1 1 2 2 3 Surge voltages that are influenced Table 9 explains the correlations by the effects of lightning can also have between lightning zone transitions and a negative impact on the functioning the IEC category of the MCR protective Corresponds to and availability of electronic modules in devices in comparison to the power SPD type D1 C2 C3 measurement and control technology. supply protective devices. IEC-61643-21 Damage caused by surge voltages in In contrast to installing SPDs for Corresponds to MCR technology systems can, however, power supply systems, a surge protective SPD type 123 be effectively prevented by using device does not have to be installed IEC-61643-11 tailor-made surge protective devices. at every zone transition in the case of Depending on the potential for risk MCR signals (refer to IEC 61643-22). In Table 9: Lightning protection zone transitions and and the requirements of the protection practice, the signal cabling from the field corresponding SPD types

46 PHOENIX CONTACT The basics of surge protection | Areas of application

Choosing surge protective devices insulated from the ground potential voltage protection level. Selecting surge protective devices for for interference immunity. A frequently The special functioning of the MCR technology depends on several encountered application of this type protective circuit with decoupling factors. The product required is is the 4 ... 20 mA current loop for resistors is described in detail below. primarily determined by the type of transmitting measured values. In cases where the decoupling signal circuit to be protected. To ensure insulation in the application resistors in the common mode paths Typical signal transmissions are: does not fail going forward, the are damaging, it makes sense to choose • Binary signals surge protective devices are designed a circuit version without decoupling. • Analog loops accordingly. Gas-filled surge protective This may be the case with the Pt 100 • Temperature measurements (two-, devices (gas discharge tubes, GDT) have two-conductor measuring circuits. three-, and four-terminal sensing) a corresponding insulation behavior. • Multi-polar binary signals When operated, they guarantee insulation between the signal wires and Other factors involved in selection are: the ground potential. In the event that • Signal voltage of the signal to be a surge voltage is applied, the GDT transmitted effectively discharges the transients to • Surge withstand capability of the end ground and limits the voltage so that device interface to be protected the dielectric strength of the end device • Transmission frequency of the signal is not exceeded. The typical dielectric strength of the end device is 1.5 kV. Surge protection for all signal 6.4.1 How the In addition to protecting the dielectric types circuits work strength, the protection between the The huge variety of different signal signal wires and thereby the electric types, field buses, and interfaces Basic circuits strength is particularly important in the requires a tailor-made product In measurement and control technology, area of MCR surge protection. The end and a wide product range. When there are different applications and types devices are often much more sensitive choosing the right MCR SPD, of signal. Various protective circuits are to potential differences of this nature, the STOP-IT (Selection Tool therefore available that are specially as sensitive semiconductor components of Protection for Information optimized for the application. First of in the terminal device are directly Technology) selection guide is all, a distinction is made between signal affected. Often, the corresponding invaluable. It is available online on types that are designed as a closed electric strength of the devices is below the Phoenix Contact website. circle (loop) and signals with a common 100 V. The protection stage affected in reference potential or a shared return the surge protective device implements conductor. a fast-responding suppressor diode The stand-alone closed circles (loops) (transient voltage suppressor diode, are often designed so that they are TVS diode), with a correspondingly high

Signal Signal

Ground Ground

Fig. 72: Basic circuit for insulated signal circuits Fig. 73: Basic circuit for insulated signal circuits (without coupling resistors)

PHOENIX CONTACT 47 The basics of surge protection | Areas of application

where the resistors can falsify the measuring result. Even in the event of Unprotected ΔU Protected actuator circuits with higher nominal currents, this type of protective circuit Decoupling resistor is used. Transient Surge voltage U Applications with common reference UG S potential require another protective circuit, as the sensitive semiconductor Gas-filled surge ΔU Suppressor diode arrester components in the end devices can also for Field Decoupling resistor be damaged by transient overvoltages protected device between the signal wires and the Strike voltage UG=2xΔU+US reference potential. For this reason, in such cases the TVS diodes are switched Fig. 76: Two-stage protective circuit between each wire and the reference potential. In cases where the reference potential is grounded, the surge protective device (Fig. 76). Due to the operating voltage of the application. protective device can be used, as shown low response voltage, the suppressor The products are designed in such a in Fig. 74. In the majority of cases, a diode is initially low-resistance. It results way that not only an individual transient, direct connection between the common in a compensating current across the but many overvoltage events can be reference potential (e.g., ground) and coupling resistors and the diode. Due mastered. The testing and maintenance the ground potential is not permitted to the voltage drop on the diode and intervals can be set up accordingly for or desired. To nevertheless be able resistors, a voltage arises that reaches the systems. Depending on the risk to provide protection to insulate the the level of the strike voltage of the gas- assessment, in practice, SPDs tests are system from the ground potential, circuit filled surge protective device. As soon carried out every one to four years. versions with additional gas-filled surge as this also becomes low-resistance, protective devices are a logical choice it discharges the power of the surge (Fig. 75). voltage. The circuit is designed in such a How the coupling elements work way that the gas-filled surge protective Coupling elements increase the device is fully activated before the diode performance of the protective circuit if reaches the performance limit. Once the a particularly large pulse between two transient is no longer present, the short- signal wires has to be limited. The surge circuit current is extinguished, as the voltage from the field side is applied arc burn voltage of the gas-filled surge to the unprotected side of the surge protective device is higher than the

Signal 1

Signal 1

Signal 2

Signal 2

Reference

Ground

Ground

Fig. 74: Basic circuit for applications with common reference potential, Fig. 75: Basic circuit for applications with common reference potential, directly grounded indirectly grounded

48 PHOENIX CONTACT The basics of surge protection | Areas of application

6.4.2 Function-monitored device series. Here the signal is also protection displayed visually and made available via PLUGTRAB PT-IQ a floating contact as a remote warning Thanks to this system, the user The PLUGTRAB PT-IQ protective signal. Via this floating contact, the knows the status of their system device system (Fig. 77) is an especially status of the SPDs can be forwarded via at any time, regardless of location. convenient solution. The SPDs monitor the various transmission media (bus or The devices are available with themselves, thanks to an intelligent wireless systems). screw terminal blocks or with monitoring system. They report the a Push-in connection. Another respective function status. For this version is suitable for use in Ex i purpose there are LED indicators on circuits. the protective plug in green, yellow, and red. Yellow indicates that the protective device is reaching the end of its service life. Yellow means that the protective function is still fully guaranteed. This early warning indicator enables the replacement to be planned at an early stage. A replacement is recommended and must be carried out when the red LED lights up at the latest. A pluggable signal and supply bus runs along the DIN rail, thereby minimizing wiring effort. The protective modules receive the supply voltage from this and report their status to the central controller at the start of the protective Fig. 77: PT-IQ protective device system with function status display

Fig. 78: Coupled surge voltages on signal lines in a sewage works

PHOENIX CONTACT 49 The basics of surge protection | Areas of application

6.4.3 Protection in the field and the control center Field Control center

In most cases, transient overvoltages SPD arise on signal lines due to indirect couplings. Systems that are particularly

at risk are those that are very extensive SPD and those that have high numbers of lines laid through the free-standing area (LPZ 0) (strong meshing) (Fig. 78). Be aware that the hazards must be made clear at both end points of the Fig. 79: Surge protection in the field and the control center lines. It is therefore recommended that the surge protection is taken into account both in the field as well as in applies to surge protective devices that such applications, take note of the the control center (Fig. 79). are used in these types of application. corresponding approval. Systems often contain signal circuits Today's requirements with Ex i protection (intrinsic safety) Zone 0 The surge protection products that according to IEC/EN 60079-11. A circuit Area in which a hazardous explosive gas are mounted on a DIN rail often, is described as intrinsically safe if the atmosphere is present for continuous, in line with today's state-of-the-art current and voltage are limited to such frequent or long periods. These technology, have an installed, galvanic an extent that no spark or thermal conditions are usually present inside conductive base contact that is designed effect can cause a potentially explosive containers, pipelines, apparatus, and to discharge the transients to ground. atmosphere to ignite. No special tanks. This means that the connection to the authorization (e.g., fire certificate) equipotential bonding on the DIN rail is required for the maintenance of Zone 1 can be made to ground. For installation intrinsically safe circuits. The cables Area in which a hazardous explosive in the field, special designs are available of the intrinsically safe circuits can be gas atmosphere is to be expected only that can be directly attached to the short circuited or interrupted without occasionally during normal operation. threaded screws on the measuring having to de-energize the system. On This includes the immediate area transducers or actuators. The protective top of this, the equipment may be surrounding zone 0, as well as areas circuits are enclosed in a stable metal installed in EX zone 0, depending on close to filling and emptying equipment. housing and have an IP protection class the respective protection level. If surge which enables direct use in open areas. protective devices are to be used in In this case, the discharge to ground takes place via the local equipotential bonding connection on the field device. Certified protective devices 6.4.4 Surge protection for potentially explosive areas in explosion-proof areas With the PLUGTRAB, TERMITRAB, and SURGETRAB Explosive atmospheres can frequently product ranges, Phoenix Contact occur in the chemical and petrochemical provides solutions that have ATEX industries due to industrial processes. approval according to directive They are caused, for example, by gases, 94/9/EC and that can be installed fumes or vapors. Explosive atmospheres in intrinsically safe circuits up to are also likely to occur in mills, silos, and Zone 1. sugar and fodder factories due to the dust present there. Therefore, electrical devices in potentially explosive areas are Fig. 80: Surge protection for direct mounting on subject to special directives. This also field devices, SURGETRAB

50 PHOENIX CONTACT The basics of surge protection | Areas of application

Zone 2 Area in which a hazardous, explosive gas atmosphere is not expected during normal operation; however if it does Zone 2 occur, it is only for a short time. Zone 2 includes areas that are used exclusively for storage, areas around pipe connections that can be disconnected, Zone 1 and generally the intermediate area surrounding Zone 1.

6.4.5 Lightning protection equipotential bonding for Zone 0 pipelines

A long service life is vital for the cost- effective operation of pipelines. Active corrosion protection systems are used to protect against rust. These require the metal pipes to be insulated against Fig. 81: Zone division based on the example of a liquid tank with fill level sensor ground potential for operation. In order to protect the pipe insulation (coating) and the insulating flanges against damage caused by surge voltages, isolating spark gaps are used (Fig. 83). If a surge voltage occurs, for example due to a lightning strike, the isolating spark gap becomes low-resistance. The lightning current is discharged to ground via a specific route, thereby ensuring lightning protection equipotential bonding.

Fig. 82: Typical area of application: gas compression station Fig. 83: Installation example based on an insulated flange

PHOENIX CONTACT 51 The basics of surge protection | Areas of application

6.5 Protection of signal transmission circuits in information technology

Communication via data networks is gas- filled surge protective devices. Where to Cat. 6 and Cat. 7, and in the future a part of daily life in all areas of the required by the circuit technology, ohmic will work according to Cat. 8.1 or company. resistors decouple the two protection Cat. 8.2. The interfaces operate with low signal stages. Protective devices with RJ45 levels at high frequencies. This makes connection, where all eight signal paths them particularly sensitive to surge 6.5.1 Ethernet and token ring are protected, are universally suited to voltages and can lead to the destruction interface the Ethernet, Profinet, and token ring of electronic components in IT systems. interfaces. In addition to protection that is tailored The architecture or structure of a to these systems, SPDs must also exhibit network installation and the type of Power over Ethernet (PoE) high-quality signal transmission behavior, data transfer between the terminals in Power over Ethernet (PoE) is a process as otherwise malfunctions are to be the data network are referred to as the in which the auxiliary energy for the expected in the data transmission. This topology. connected devices is also transmitted via aspect is becoming ever more important In local networks, they have been the Ethernet data cable. in the face of constantly increasing data tried and tested as bus, ring, and star The auxiliary power is either applied transmission rates. To this end, when topologies that can also be combined. to the unused wire pair (mode b, Fig. developing new SPDs for IT systems, To transmit information in data networks, 86) or is supplied between the signal the focus is on implementing high-quality twisted pair or fiber optics are used. wire pairs as phantom power (mode A, signal transmission behavior. It is Fig. 85). In line with IEEE 802.3af, a evaluated based on the ISO/IEC 11801 Data transmission requirements maximum power of 13.5 W can be or EN 50173 standards. Ethernet and token ring interfaces transmitted using this procedure. The Furthermore, in this area of have been used for years. Ethernet following IEEE 802.3at standard already application, a wide range of connection systems have prevailed, however, due to enables 25.5 W with PoE. POE++ is technology is encountered. For their transmission speed and compact being debated, with which even higher this reason the protective devices connectors. The transmission behavior transmission capacities will be able to be must correspond to the electrical of the Ethernet system is defined in achieved. specifications and also be adapted to standard IEEE 802.3. The transmission the interfaces to be protected. The SPD speed is up to 10 Gbps. 6.5.2 Serial interfaces versions often differ only in their design The transmission speed (Table 5.1.1a) and connection technology. is defined according to the power Serial interfaces are used to exchange The protective circuits usually categories (Cat. 5 - Cat. 7). data between computers and peripheral combine fast-responding, low-capacitive New systems with a higher devices. In the event of serial data suppressor diodes with powerful, transmission frequency work according transmission, the bits are transmitted

DT-LAN-Cat.6+ 21 3 64OUT 57 8 The DT-LAN-CAT.6+ protective device optimally protects sensitive equipment, as quickly reacting protective components are used for the data cabling as well as for the PoE system.

21 3 64IN 57 8

Fig. 84: DT-LAN-Cat.6+ - SPD for information technology

52 PHOENIX CONTACT The basics of surge protection | Areas of application

Area of application Category Mbps Cable Connection

100 Base TX LAN, structured RJ45, pair: 1-2, 3-6, or 5 100 2 - 4-pair twisted pair (Fast Ethernet) building cabling 4-5, 7-8

1000Base T LAN, structured RJ45, pair: 5e, 6 1000 4-pair twisted pair (GIGABIT Ethernet) building cabling 1-2, 3-6, + 4-5, 7-8

10 GBase T LAN, structured RJ45, pair: 6a 10,000 4-pair twisted pair (GIGABIT Ethernet) building cabling 1-2, 3-6, + 4-5, 7-8

10 GBase T LAN, structured RJ45, pair: 7 10,000 4-pair twisted pair (GIGABIT Ethernet) building cabling 1-2, 3-6, + 4-5, 7-8

Table 10: Transmission speed vs. performance categories

3 3 receive signal are each transmitted via a 6 pair of signal wires. In addition, a ground 7 is routed as a reference potential, so

50 V 50 V that defined voltage conditions prevail at up to 57 V 8 up to 57 4 (30 W) V (30 W) the connected interfaces. 5 1 TTY interface 1 2 2 The TTY interface works serially and symmetrically via two signal wire pairs. Fig. 85: Transmission of auxiliary power by means Fig. 86: Transmission of auxiliary power by means When a signal voltage of up to 24 V of phantom supply (mode A) of phantom supply (mode B) occurs, a current signal is analyzed. Here, 10 – 30 mA is the logical 1 and 0 – 1 mA the logical 0. Standard data over a cable (in series), one after the D-SUB attachment plugs for DIN transmission rates are 9.6 kbps or other. Particularly common are: rail mounting or DIN rail modules with 19.2 kbps. screw terminal blocks are frequently RS-485 and PROFIBUS interfaces used as protective devices. The RS-485 serial interface is used on the Intel bitbus and is closely related V.24 interface to the RS-422. This symmetrical data The V.24 or RS-232 serial interface transmission generally functions via a works with an asymmetrical signal pair of signal wires. Versions with two transmission. One transmit and one pairs of signal wires and a ground are receive signal each have a common also used. reference potential (ground). In In older systems, the signal voltage of addition, up to five control signals can this interface amounts to ground -7 V be transmitted. This yields a maximum and +12 V. In newer systems, a version of eight active signals including ground. with TTL level, e.g., +/- 5 V is used. Connection is usually via D-SUB 25, The PROFIBUS interface is a further D-SUB 9 or screw terminal blocks. development of the RS-485 interface. It uses the physical characteristics of V.11 interface the RS-485, but with transmission rates The V.11 or RS-422 serial interface of up to 12 Mbps. These interfaces are works on the basis of symmetrical signal used for other applications in the time transmission. The transmission path and machine data acquisition device field. can be up to 1000 m. The transmit and

PHOENIX CONTACT 53 The basics of surge protection | Areas of application

6.6 Protection of signal transmission circuits in telecommunications technology

Telecommunication end devices the three-electrode gas discharge Analog telecommunications are today an inherent part of office tubes are equipped with thermal interface electronics. Today, unrestricted protection. Common interfaces in Today, analog telecommunication is only operational availability of modern, fast telecommunications are: found in simple telephone connections. communication systems is an absolute Protective devices for this should have necessity, especially in the business xDSL interface nominal voltages of 180 V. Generally, sector. The specific use of suitable DSL interfaces (digital subscriber DSL protective devices (Fig. 87) can also surge protective devices can prevent line) provide Internet connections be used for analog telecommunication. the sudden and unforeseen failure with speeds of 1 Mbps (ADSL) up to of important telecommunications 100 Mbps (VDSL). The transmission equipment. Suitable protective devices frequency is between 2.2 MHz and for DSL data transmission and for analog 17.7 MHz. The nominal voltage for the signal interfaces are available. protective circuit on suitable protective The protective circuit is mainly devices depends on whether a DC made up of a combination of Trisil supply is also transmitted. Typical diodes and powerful, gas-filled surge nominal voltage values for applications protective devices. The gas-filled surge are: protective devices are designed as • Without power supply: < 24 V DC three-electrode gas discharge tubes. • With power supply: ≥ 110 V DC The central electrode provides common When compared internationally, the mode voltage protection on the transmission frequency in the DSL range ground. Where required by the circuit can vary by some 100 kHz depending on technology, ohmic resistors decouple the the region. For this reason, their cut-off two protection stages. frequency should be taken into account To protect against voltages from the when selecting a protective device. power supply network (power cross)

DT-TELE-RJ45

Plug

RJ 45 RJ 12 RJ 45 Plug RJ 11 RJ 12 RJ 11 The DT-TELE-RJ45 protective Aa 2 3 4 2 3 4 Aa device protects fast VDSL connections with its very low Ab 3 4 5 3 4 5 Ab attenuation. Thanks to the unprotected protected universal connection technology Ba 1 2 3 1 2 3 Ba (RJ45, RJ12, RJ11, and pluggable screw connection) the product is Bb 4 5 6 4 5 6 Bb ideal for any application.

Fig 87: DT-TELE-RJ45 - SPD for telecommunications systems

54 PHOENIX CONTACT The basics of surge protection | Areas of application

6.7 Protection of signal transmission circuits in transceiver systems

Transceiver systems are generally advantage in this technology is achieving to sport and leisure facilities. The considered to be particularly susceptible a very good (low) voltage protection permanent availability of this monitoring to surge voltages. level, as the protective device functions equipment requires suitable surge Antenna cables which extend beyond as a short circuit in the frequency range protective devices. As a general rule, the building and are generally particularly of surge voltages. However, it must be coaxial attachment plugs are used as long, as well as the antennas themselves, taken into account that the cable that is protective devices, with BNC or TNC are directly exposed to atmospheric connected to the Lambda/4-protective connectors. discharges. For this reason, cables device cannot use a DC power supply. with a coaxial structure and therefore Relatively wide bandwidth signals Radio link and mobile phone favorable EMC properties are used. The (e.g., 0.8 – 2.25 GHz) can be transmitted systems shield of the antenna cable can be either by means of HF-optimized Lambda/4 Radio link technology enables wireless grounded or floating, depending on the protective devices. Fig. 88 shows a transmission of data. The radio waves system conditions. However, the risk of typical design of a protective device with produced are transmitted in multiplex surge voltage coupling in antenna cables Lambda/4 technology. mode using panel antennas with a carrier is not completely eliminated. Surge The most common applications for SPDs frequency of between 1 and 40 GHz. voltages can even reach the sensitive in telecommunications are: Common types of antennas are parabolic interfaces of transceiver systems via this reflectors, shell antennas, and horn cable path. Antenna connection of television antennas. The nominal frequencies of The high frequencies of wireless and radio receivers useful signals in this range are between transmission require the use of The protective devices for radio and 0.8 GHz and 2.7 GHz. N, SMA or 7/16 protective devices with low self- television devices are generally mounted connectors are used as the connection capacitance or low insertion loss with between the antenna wall connection technology for the protective devices. good impedance matching. Nevertheless, and the outgoing antenna cable. For a good level of protection is required satellite receivers, there are multi- with high discharge capacity. For this channel protective devices for wall reason, most protective devices are mounting. Broadband cable and antenna equipped with powerful gas-filled surge connections generally have TV and RF protective devices or with the Lambda/4 connectors according to DIN 45 325. technology. The Lambda/4 technology Satellite receivers are connected via F uses a short circuit between the inner connectors. conductor and the shield. The length of the cable between the short circuit Video communication and the inner conductor matches The applications in video communication the frequency that is allowed to pass extend from monitoring buildings, through without attenuation. A great public areas, and institutes right through

CN-LAMBDA/4 Using the CN-LAMBDA/4-2.25 protective device, the widest range of transmission systems can be actively protected in the λ/4 GHz range. This is achieved by means of a broadband LAMBDA/4 technology.

Fig. 88: CN-LAMBDA/4 - protective device with Lambda/4 technology

PHOENIX CONTACT 55 The basics of surge protection | Glossary

7 Glossary

ATEX current parameter values with regard Nominal discharge current (In) ATEX is a widely used synonym for the to probability, whereby the largest and Peak value of the current flowing ATEX directive issued by the European smallest measured values in the event through the SPD with pulse shape Union. The ATEX designation is derived of naturally occurring strikes cannot be (8/20 μs). The pulse shape (8/20 μs) of from the French abbreviation for exceeded and the strikes can be safely a surge current is characteristic of the “atmosphères explosibles”. discharged. Lightning Protection Level effects of an indirect lightning strike or I thereby corresponds to the highest switching operation. The value of the Binary signals measured values and the greatest nominal discharge current is used for By binary signals, we mean digital signals probability of capturing a strike. The a variety of tests on an SPD, including that only take on the state of “high” or values decrease accordingly, down to those used to determine the voltage “low”. Generally, these signals relate to a Lightning Protection Level IV. protection level. Depending on the common reference potential or a shared Lightning Protection Level assigned return conductor. Lightning protection system to a lightning protection system, the System consisting of interception rods, SPDs must have minimum values that Dielectric strength protective devices, and grounding system correspond to this value. Insulation strength of the electrical externally, as well as equipotential circuits of a piece of equipment when bonding system and coordinated SPD Nominal load current (IL) compared to withstand and surge system within the structural system Maximum r.m.s. value of the nominal voltages with amplitudes above the to protect against damage caused by current, which allows a connected ohmic maximum continuous voltage. surge voltages and surge currents from load to flow to one of the protected lightning strikes. outputs of the SPD. This maximum EMC value is specified by the parts carrying EMC stands for electromagnetic Lightning protection zone operational current within the SPDs; compatibility, the capacity of an A zone in which the electromagnetic these must be able to withstand the apparatus, plant or system to work environment is determined with regard continuous thermal current load. satisfactorily in an electromagnetic to risk of lightning. All the (supply) lines environment, without causing that cross zone limits must be included Nominal voltage (UN) electromagnetic interference itself that in the lightning protection equipotential The nominal value of the voltage of the would be unacceptable for the apparatus, bonding by means of corresponding current or signal circuit based on the plants or system in this setting. SPDs. The zone limits of a lightning zone use envisaged for the SPDs. The nominal are not necessarily physical limits (e.g., voltage stated for an SPD corresponds Gas discharge tube, GDT walls, floor or ceiling). to the system voltage of the typical SPD Gas-filled surge protective device installation site for a standard three- Lightning protection zone, LPZ phase system, e.g., 230/400 V AC. Lower Insertion loss Lightning protection zone system voltages can also be protected by The attenuation value is defined as the the SPD. In the event of higher system ratio of voltages that occur immediately Maximum continuous voltage (Uc) voltages, it must be decided on a case- before and after the insertion point of Maximum r.m.s. value of the voltage that to-case basis as to whether the SPD can the protective device to be tested. The can continuously be applied to the mode be used and if there are restrictions to result is expressed in decibels. of protection of the SPDs. The maximum observe. continuous voltage must be at least 10% Lightning Protection Level higher than the value of the nominal Off-load voltage (UOC) A regulatory division of lightning voltage. In systems with greater voltage Off-load voltage of the hybrid generator protection systems into classes I to IV, fluctuations, SPDs with a greater difference at the terminal points of the SPD. A which are based on a set of lightning between UC and UN must be used. hybrid generator creates a combined

56 PHOENIX CONTACT The basics of surge protection | Glossary

surge; e.g., in off-load, it supplies a capacity indicates the prospective r.m.s. TVS voltage pulse with a defined pulse shape, value of the short-circuit current at TVS stands for Transient Voltage generally (1.2/50 μs), and in a short the installation location of a voltage- Supressor. circuit, a current pulse with a defined switching SPD, up to which the SPD Overvoltage categoryDivision of pulse shape, generally (8/20 μs). The once again transitions into a high ohmic equipment into categories I to IV combined surge is characteristic of the state if the maximum Uc continuous depending on their surge voltage effects of an induced surge voltage. voltage is being independently applied resistance. Overvoltage category Depending on the protection class due to a surge current, without I corresponds to the lowest value assigned to a lightning protection system, triggering an upstream overcurrent and consists of particularly sensitive the SPDs must have minimum values that protective device. (end) devices. These values increase correspond to this value. accordingly, up to overvoltage category Short-circuit withstand capability IV. The values for the individual Overcurrent protective device, (ISCCR) categories also depend on the voltage OCPD Maximum uninfluenced short-circuit level of the power supply system. Overcurrent protective device current of the electrical network, for which the SPD is rated in conjunction Voltage protection level (Up) Power over Ethernet, PoE with the upstream overcurrent Maximum voltage that can occur on the Power over Ethernet is a process in protective device. The short-circuit connection terminal blocks of the SPD which the auxiliary energy for the withstand capability indicates up to while loaded with a pulse of specific connected devices is also transmitted via which prospective short-circuit current voltage steepness and a discharge surge the Ethernet data cable. the SPD can be used at the installation current of specified amplitude and wave location. The corresponding tests form. This value characterizes the surge Pulse discharge current (Iimp) to determine this value are carried voltage protective effect of the SPD. In Peak value of the current flowing out in connection with the upstream the event of a surge voltage phenomenon through the SPD with pulse shape overcurrent protective device. In the within the performance parameters of (10/350 μs). The pulse shape (10/350 event that the special surge protective the SPDs, the voltage is safely limited to μs) of a surge current is characteristic devices for PV systems correspond to a maximum of this value at the protected of the effects of a direct lightning the value ISCPV, this is the max. direct connections of the SPD. strike. The value of the pulse discharge current short-circuit current of a system current is used for special SPD tests up to which the the SPD may be used. to demonstrate carrying capacity with regard to high-energy lightning currents. Surge current According to the Lightning Protection A pulse-shaped current that is Level assigned to a lightning protection characterized by a significant rise in system, the SPDs must have minimum current within a short period of time. values that correspond to this value. Typical pulse shapes are (8/20 μs), with which the voltage-limiting behavior of Safe Energy Control technology, SPDs can be checked, and (10/350 μs), SEC technology with which the lightning current capacity Technology for SPDs for protecting the of the SPDs can be tested. power supply. SPDs with SEC technology are characterized by the following: Surge protective device, SPD • Impact-free and durable Surge protective device • Backup-fuse-free solution for every application Surge voltage • Compact and consistent pluggable A pulse-shaped voltage that is characterized design by a significant rise in voltage within a short period of time. A typical pulse shape Sequential current extinguishing is (1.2/50 μs). The response behavior of capacity (I ) fi SPDs or the surge voltage resistance of The sequential current extinguishing equipment can also be tested with this.

PHOENIX CONTACT 57 The basics of surge protection | Glossary

58 PHOENIX CONTACT The basics of surge protection | References

8 References

[1] International Electrotechnical Commission. IEC 62305-1 - Lightning protection - Part 1: General principles. s.l. : VDE Verlag GmbH, 2010. [2] International Electrotechnical Commission. IEC 62305-2 - Lightning protection - Part 2: Risk management. s.l. : VDE Verlag GmbH, 2010. [3] International Electrotechnical Commission. IEC 62305-3 - Lightning protection - Part 3: Physical damage to structures and life hazard. s.l. : VDE Verlag GmbH, 2010. [4] International Electrotechnical Commission. IEC 62305-4 - Lightning protection - Part 4: Protection against lightning. Electrical and electronic systems within structures. s.l. : VDE Verlag GmbH, 2010. [5] International Electrotechnical Commission. IEC 60364-4-44 - Low-voltage electrical installations - Part 4-44: Protection for safety - Protection against voltage disturbances and electromagnetic disturbances. s.l. : VDE Verlag GmbH, 2007. [6] International Electrotechnical Commission. IEC 61643-11 - Surge protective devices connected to low-voltage power systems - requirements and test methods. s.l. : VDE Verlag GmbH, 2011. [7] International Electrotechnical Commission. IEC 61643-21 - Surge protective devices connected to telecommunications and signaling networks - Performance requirements and testing methods. s.l. : VDE Verlag GmbH, 2000. [8] International Electrotechnical Commission. IEC 61643-31 - Low-voltage surge protective devices – requirements and tests for surge protective devices to be used in photovoltaic installations. s.l. : VDE Verlag GmbH, 2015. [9] International Electrotechnical Commission. IEC 60664-1 - Insulation coordination for equipment within low-voltage systems - Part 1: Principles, requirements, and tests. s.l. : VDE Verlag GmbH, 2007. [10] International Electrotechnical Commission. IEC 60364-1 - Low-voltage electrical installations - Part 1: Fundamental principles, assessment of general characteristics, definitions. s.l. : VDE Verlag GmbH, 2005. [11] International Electrotechnical Commission. IEC 60364-5-53 - Electrical installations of buildings - Part 5: Selection and erection of electrical equipment; Section 53: Switchgear and control. s.l. : VDE Verlag GmbH, 2002. [12] International Electrotechnical Commission. IEC 60364-4-43 - Low-voltage electrical installations - Part 4-43: Protection for safety - Protection against overcurrent. s.l. : VDE Verlag GmbH, 2008. [13] European Committee for Electrotechnical Standardization. CLC/TS 50539-12 - Low-voltage surge protective devices connected to photovoltaic installations - Selection and application principles. s.l. : VDE Verlag GmbH, 2013. [14] Phoenix Contact GmbH & Co. KG. TRABTECH surge protection - user manual for specialist electrical planners. 2015. [15] International Electrotechnical Commission. IEC 61643-12 - Surge protective devices connected to low-voltage power systems - Selection and application principles. s.l. : VDE Verlag GmbH, 2010. [16] International Electrotechnical Commission. IEC 61643-22 - Low-voltage surge protective devices - Surge protective devices connected to telecommunications and signaling - Selection and application principles. s.l. : VDE Verlag GmbH, 2007.

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