Lightning-Induced Overvoltages in Low-Voltage Systems

Total Page:16

File Type:pdf, Size:1020Kb

Lightning-Induced Overvoltages in Low-Voltage Systems NEI-NO--1063 N09905100 Hans Kristian Hoidalen Lightning-induced overvoltages in low-voltage systems REO 2 9 ES3 OST1 universitet Trondheim mm&ng ’Srna*"* NT NT teknisk-naturvitenskapelige Norges LIGHTNING-INDUCED OVERVOLTAGES IN LOW-VOLTAGE SYSTEMS by Hans Kristian Heidalen A dissertation submitted to the Norwegian University of Science and Technology Department of Electrical Power Engineering in partial fulfilment of the requirements for the degree of Doktor Ingenior December 1997 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Preface 111 PREFACE This thesis is the result of a research project founded by the Norwegian Research Council. All the work was carried out at the Department of Electrical Power Engineering at the Norwegian University of Science and Technology (NTNU) during the years 1994-1997. I would especially express my gratitude to my supervisors Prof. Jarle Sletbak at NTNU and Dr.ing. Thor Henriksen at the Norwegian Electric Power Research Institute (EFI) for being an outstanding source of inspiration (and perspiration) during this work. I would also like to thank all the other institutions and individuals making this thesis possible. In order of appearance: Jostein Huse at EFI, Institute of High Voltage Research at University of Uppsala, University of Florida, the three diploma students Kurt A. Bakke, Abraham T. Gerezgiher and Morten Nordskog, Siemens installasjon, AB Elektro, Det Norske Meteorologiske Institute and Trondheim Energiverk. Finally, I would like to thank all my friends and colleagues at the Department of Electrical Engineering for valuable assistance and encouragement during these three years. Trondheim, December 1997 Hans Kr. Hoidalen Abstract v ABSTRACT Lightning-induced overvoltages (LIOs) from nearby lightning are a main source of failures in low-voltage overhead line systems. Lightning strokes closer than about 1 km can cause harmful overvoltages, which in turn can lead to direct or delayed damages to connected electrical installations or equipment. Insurance companies report an increasing number of damages of electric nature over the years. This increase is probably caused by the introduction of more and more sensitive electrical equipment in an increasing number of installations. This thesis deals primarily with calculations of lightning-induced overvoltages (LIOs) in low- voltage overhead line systems with the objective to enable the design of a proper overvoltage protection. The work is divided in two parts: 1) Development of calculation models 2) Calculations of LIOs in low-voltage systems In the first part models for calculation of LIOs are adapted from the literature or developed based on measurements. An objective when selecting the models is to aim at simple models based on a few measurable quantities, and which show a reasonable accuracy. The models used in this thesis are believed to be fairly accurate for the first few microseconds, which normally is sufficient for prediction of the maximum induced voltage in the system. The lightning channel is modelled by the Modified Transmission Line (MTL) model with the Transmission Line (IL) model as a special case. The coupling between the electrical fields from a lightning channel and an overhead line is modelled by Agrawal ’s model. The attenuation of electrical fields propagating over a lossy ground is modelled by Norton ’s- or the Surface Impedance methods. All these models are well known in the literature and are in this work synthesised to enable calculation of LIOs in practical low-voltage configurations using the electromagnetic transients program, ATP-EMTP. The validity of all the applied models is analysed. In addition measurements have been performed in order to develop models of distribution transformers and low-voltage power installation (LVPI) networks. Simple models of "typical" transformers and LVPIs are developed for calculations when specific data are unavailable. The practical range of values and its influence on the LIOs in a system is investigated. The main frequency range of interest related to LIOs is 10 kHz - 1 MHz in which all the models are accurate. In the second part the adapted or developed models are used to calculate LIOs in low-voltage systems. The influence of various key parameters in the systems is investigated. Of greatest importance are the return stroke amplitude and rise time, the overhead line height and location, the termination of overhead line segments, neutral grounding, and the ground conductivity. • The LIOs in an unprotected system increase proportionally to the return stroke amplitude. Larger rise times of the return stroke result in lower LIOs. • The introduction of lower terminating impedances by connecting e.g. more LVPI networks results in lower LIO. Thus the magnitude of the LIO is likely to be highest in rural areas with few installations connected to an overhead line. A transformer with a Abstract Vi grounded LV neutral can be modelled as a small inductance (4-40 pH) closely related to the transformer ’s rated power and voltage. When the neutral is isolated the model becomes capacitive and the LIOs increases considerably. As a first approximation, LVPI in TN-systems can be modelled as a small inductance (2-20 pH) and in the IT-system as a capacitance (20-200 nF) in series with the inductance found in the TN-system. The influence of type of wiring and apparatus is analysed. The maximum LIO in LVPI networks supplied by an underground cable from an overhead line system is normally little affected by this cable. • An IT-system results in much higher LIO phase-to-ground than a TN-system and this can explain why the number of transients and damages is large in Norway compared to e.g. Sweden. TN-systems result on the other hand in larger phase-to-phase voltages than IT- systems. However, an IT system with a permanent ground fault will experience both high phase-to-phase and phase-to-ground voltages, compare to a TN-system. • The LIOs increase proportionally to the line height when the ground is assumed lossless. The additional contribution from a lossy ground is independent of line height. Lightning strokes near the mid-point of an overhead line results normally in the largest LIOs, but lossy ground effects may modify this. • Lossy ground effects on LIO seem to be very important. Especially in a IT-system the level of calculated LIO increases considerably when a lossy ground is taken into account. The ground losses may reverse the polarity and increase the amplitude of LIOs. However, the effect of a lossy ground is encumbered with uncertainty since a relatively high ground conductivity must be assumed in order to reproduce measurements by calculations. • To protect a low-voltage system completely from LIOs, surge protective devices must be installed at each individual installation. The level of LIOs in a TN-system is much lower and such systems is to some extent self-protected against remote lightning. Even if arresters are installed at the power service entry, large overvoltages can still arise inside the LVPI network. Oscillations due to reflections in the low-voltage system and with frequencies dependent on overhead line segment lengths could excite the natural frequency of connected LVPI circuits, resulting in large internal overvoltages. Such overvoltages can reach amplitudes of several times the protective level of the connected arrester. Contents vii CONTENTS Preface ........................................................................................................... iii Abstract ............................................................................................................... v List of symbols ........................................................................................... xi List of abbreviations ..................................................................................xii Sign conventions ..........................................................................................xii 1. Introduction ...............................................................................................1 1.1 Perspective and motivation ................................................................ 1 1.2 Objectives and contents ....................................................................... 3 2. Background .............................................................................................. 5 2.1 Introduction ......................................................................................... 5 2.2 The lightning discharge ...................................................................... 5 2.2.1 The thunder cloud 5 2.2.2 The charge separation 6 2.2.3 The discharge process 7 2.2.4 Electrical fields from lightning flash 9 2.2.5 Triggered lightning 10 2.2.6 Relative importance of field components 11 2.3 Calculating electrical fields.............................................................. 11 2.4 Lightning flash models .................................................................... 12 2.4.1 Lightning leader model 12 2.4.2 Return stroke model 13 2.5 Lossy ground effects.........................................................................14 2.6 Coupling models ............................................................................... 16 2.7 Calculations versus measurements................................................. 17 2.8 Sources ofLIO ’s..............................................................................
Recommended publications
  • Avoiding the Risks of Deadly Lightning Strikes
    Avoiding the Risks of Deadly Lightning Strikes Lightning is one of the most underrated severe weather hazards, yet ranks as the second-leading weather killer in the United States. More deadly than hurricanes or tornadoes, lightning strikes in America each year kill an average of 73 people and injure 300 others, according to NOAA's National Weather Service. How Lightning Works Lightning is caused by the attraction between positive and negative charges in the atmosphere, resulting in the buildup and discharge of electrical energy. This rapid heating and cooling of the air produces the shock wave that results in thunder. During a storm, raindrops can acquire extra electrons, which are negatively charged. These surplus electrons seek out a positive charge from the ground. As they flow from the clouds, they knock other electrons free, creating a conductive path. This path follows a zigzag shape that jumps between randomly distributed clumps of charged particles in the air. When the two charges connect, current surges through that jagged path, creating the lightning bolt. The Warning Signs High winds, rainfall, and a darkening cloud cover are the warning signs for possible cloud-to- ground lightning strikes. While many lightning casualties happen at the beginning of an approaching storm, more than 50 percent of lightning deaths occur after the thunderstorm has passed. The lightning threat diminishes after the last sound of thunder, but may persist for more than 30 minutes. When thunderstorms are in the area, but not overhead, the lightning threat can exist when skies are clear. Safety Precautions While nothing offers absolute safety from lightning, some actions can greatly reduce your risks.
    [Show full text]
  • UNIVERSAL MUSIC • Rihanna – Rihanna 777 Tour… 7Countires7days7shows DVD • Jay Sean – Neon • Jessica Sanchez
    Rihanna – Rihanna 777 Tour… 7countires7days7shows DVD Jay Sean – Neon Jessica Sanchez – Me, You & The Music New Releases From Classics And Jazz Inside!!! And more… UNI13-20 “Our assets on-line” UNIVERSAL MUSIC 2450 Victoria Park Ave., Suite 1, Willowdale, Ontario M2J 5H3 Phone: (416) 718.4000 Artwork shown may not be final The Following titles will move to I Code effective FRIDAY, APRIL 12, 2013 Artist Title Catalog UPC Price Code New Number (Current) Price Code GN'R LIES GEFMD24198 720642419823 N I GAYE MARVIN WHAT'S GOING 4400640222 044006402222 N I ON(REMASTERED URIAH HEEP DEMONS & WIZARDS 8122972 042281229725 N I SOUNDTRACK A NIGHT AT THE DRSSD50033 600445003323 SP I ROXBURY ROTH, ASHER ASLEEP IN THE BREAD B001281202 602527018355 SP I AISLE MELLENCAMP AMERICAN FOOL B000418902 602498801376 N I JOHN (COUGAR) MANOWAR LOUDER THAN HELL GEFSD24925 720642492529 SP I MALMSTEEN TRILOGY 8310732 042283107328 N I YNGWIE CRAZY FROG PRESENTS MORE CRAZY B000714902 602517018839 N I HITS ONYX BACDAFUCUP 3145234472 731452344724 N I MALMSTEEN RISING FORCE 8253242 042282532428 N I YNGWIE YOUNG NEIL OLD WAYS 0694907052 606949070526 N I MELLENCAMP SCARECROW B000451202 602498812396 N I JOHN (COUGAR) REDMAN DARE IZ A DARKSIDE 3145238462 731452384621 N I 3 DOORS DOWN ANOTHER 700 MILES B000160302 602498612477 AW I (LIVE) BON JOVI JON BLAZE OF GLORY 8464732 042284647328 N I MENDES GREATEST HITS CD3258 075021325821 N I SERGIO RICHIE LIONEL DANCING ON THE 4400383002 044003830028 N I CEILING (RE BIRDMAN FAST MONEY B000422002 602498801918 SP I SOUNDTRACK XANADU‐REMASTERED
    [Show full text]
  • Temporary Overvoltages in Power Systems - Juan A
    POWER SYSTEM TRANSIENTS – Temporary Overvoltages in Power Systems - Juan A. Martinez-Velasco, Francisco González- Molina TEMPORARY OVERVOLTAGES IN POWER SYSTEMS Juan A. Martinez-Velasco Universitat Politècnica de Catalunya, Barcelona, Spain Francisco González-Molina Universitat Rovira i Virgili, Tarragona, Spain Keywords: Ground fault overvoltages, ferro-resonance, harmonics, inrush currents, load rejection, power systems, modeling, resonance, transformer energization, transient analysis. Contents 1. Introduction 2. Modeling Guidelines for Analysis of Temporary Overvoltages 3. Faults to Ground 3.1. Introduction 3.2. Calculation of ground fault overvoltages 3.3. Case study 4. Load Rejection 4.1. Introduction 4.2. Calculation of load rejection overvoltages 4.3. Case study 4.4. Mitigation of load rejection overvoltages 4.5 Conclusion 5. Harmonic Resonance 5.1. Introduction 5.2. Resonance in linear circuits 5.3. Parallel harmonic resonance 5.4. Frequency scan 5.5. Harmonic propagation and mitigation 5.6. Case study 6. Energization of Unloaded Transformers 6.1. Introduction 6.2. Transformer inrush current 6.3. OvervoltagesUNESCO-EOLSS during transformer energization 6.4. Methods for preventing harmonic overvoltages during transformer energization 6.5. ConcludingSAMPLE remarks CHAPTERS 7. Ferro-resonance 7.1. Introduction 7.2. The ferro-resonance phenomenon 7.3. Situations favorable to ferro-resonance 7.4. Symptoms of ferro-resonance 7.5. Modeling for ferro-resonance analysis 7.6. Computational methods for ferro-resonance analysis 7.7. Case study 7.8. Methods for preventing ferro-resonance ©Encyclopedia of Life Support Systems (EOLSS) POWER SYSTEM TRANSIENTS – Temporary Overvoltages in Power Systems - Juan A. Martinez-Velasco, Francisco González- Molina 7.9. Discussion 8. Conclusion Glossary Bibliography Biographical Sketches Summary Temporary overvoltages (TOVs) are undamped or little damped power-frequency overvoltages of relatively long duration (i.e., seconds, even minutes).
    [Show full text]
  • Effects of Overvoltage on Power Consumption
    Effects of Overvoltage on Power Consumption Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy by Panagiotis Dimitriadis College of Engineering, Design and Physical Sciences Department of Electronic and Computer Engineering Brunel University London UK September 2015 ‘Oh Lord! Illuminate my darkness.’ [Saint Gregory Palamas] ii Abstract In the recent years there is an increasing need of electrical and electronic units for household, commercial and industrial use. These loads require a proper electrical power supply to convey optimal energy, i.e. kinetic, mechanical, heat, or electrical with different form. As it is known, any electrical or electronic unit in order to operate safely and satisfactory, requires that the nominal voltages provided to the power supply are kept within strict boundary values defined by the electrical standards and certainly there is no unit that can be supplied with voltage values above or below these specifications; consequently, for their correct and safe operation, priority has been given to the appropriate electrical power supply. Moreover, modern electrical and electronic equipment, in order to satisfy these demands in efficiency, reliability, with high speed and accuracy in operation, employ modern semiconductor devices in their circuitries or items. Nevertheless, these modern semiconductor devices or items appear non-linear transfer characteristics in switching mode, which create harmonic currents and finally distort the sinusoidal ac wave shape of the current and voltage supply. This dissertation proposes an analysis and synthesis of a framework specifically on what happens on power consumption in different types of loads or equipment when the nominal voltage supply increases over the permissibly limits of operation.
    [Show full text]
  • The Cruise Passengers' Rights & Remedies 2016
    PANEL SIX ADMIRALTY LAW: THE CRUISE PASSENGERS’ RIGHTS & REMEDIES 2016 245 246 ADMIRALTY LAW THE CRUISE PASSENGERS’ RIGHTS & REMEDIES 2016 Submitted By: HON. THOMAS A. DICKERSON Appellate Division, Second Department Brooklyn, NY 247 248 ADMIRALTY LAW THE CRUISE PASSENGERS’ RIGHTS & REMEDIES 2016 By Thomas A. Dickerson1 Introduction Thank you for inviting me to present on the Cruise Passengers’ Rights And Remedies 2016. For the last 40 years I have been writing about the travel consumer’s rights and remedies against airlines, cruise lines, rental car companies, taxis and ride sharing companies, hotels and resorts, tour operators, travel agents, informal travel promoters, and destination ground operators providing tours and excursions. My treatise, Travel Law, now 2,000 pages and first published in 1981, has been revised and updated 65 times, now at the rate of every 6 months. I have written over 400 legal articles and my weekly article on Travel Law is available worldwide on www.eturbonews.com Litigator During this 40 years, I spent 18 years as a consumer advocate specializing in prosecuting individual and class action cases on behalf of injured and victimized 1 Thomas A. Dickerson is an Associate Justice of the Appellate Division, Second Department of the New York State Supreme Court. Justice Dickerson is the author of Travel Law, Law Journal Press, 2016; Class Actions: The Law of 50 States, Law Journal Press, 2016; Article 9 [New York State Class Actions] of Weinstein, Korn & Miller, New York Civil Practice CPLR, Lexis-Nexis (MB), 2016; Consumer Protection Chapter 111 in Commercial Litigation In New York State Courts: Fourth Edition (Robert L.
    [Show full text]
  • RECM0018E.Pdf
    ICAR REC M 0018 E International Commission for Alpine Rescue Commission for Mountain Emergency Medicine Recommendation REC M 0018 of the Commission for Mountain Emergency Medicine of 2005 LIGHTNING INJURIES: PREVENTION AND ON–SITE TREATMENT IN MOUNTAINS AND REMOTE AREAS Intended for Physicians, First Responders, Mountaineers Ken Zafren, Bruno Durrer, Jean-Piere Herry, Hermann Brugger Official guidelines of the International Commission for Mountain Emergency Medicine and the Medical Commission of the International Mountaineering and Climbing Federation (IKAR und UIAA MEDCOM) Reprinted from Publication RESUSCITATION, V65(3): 369-372, Zafren K: Lightning injuries: prevention and on-site treat- ment in mountains and remote areas. Official guidelines of the International Commission for Mountain Emergency Medicine and the Medical Commission of the International Mountaineering and Climbing Federation (ICAR and UIAA MEDCOM) © 2005 Elsevier Ireland Ltd. Hypertext link: http://www.sciencedirect.com/science/journal/03009572 SHORT COMMUNICATION LIGHTNING INJURIES: PREVENTION AND ON-SITE TREATMENT IN MOUNTAINS AND REMOTE AREAS. OFFICIAL GUIDELINES OF THE INTERNATIONAL COMMISSION FOR MOUNTAIN EMER- GENCY MEDICINE AND THE MEDICAL COMMISSION OF THE INTERNATIONAL MOUNTAINEERING AND CLIMBING FEDERATION (ICAR AND UIAA MEDCOM) Intended for physicians, paramedics and mountaineers Ken Zafren a, Bruno Durrer b, Jean-Pierre Herry c, Hermann Brugger d,* a Division of Emergency Medicine – Stanford University Medical Center, Stanford, CA, 10181 Curvi St., Anchor- age, AK 99507 USA b The Medical Commission of the International Mountaineering and Climbing Federation, CH-3822 Lauterbrunnen, Switzerland c The Medical Commission of the International Mountaineering and Climbing Federation, Ecole National de Ski et d'Alpinisme, Route du Bouchet, F-74400 Chamonix, France d The International Commission for Mountain Emergency Medicine, Europastrasse 17, I-39031 Bruneck, Italy * Corresponding author.
    [Show full text]
  • Transient Overvoltages in Power System
    PRATIBHA: INTERNATIONAL JOURNAL OF SCIENCE, SPIRITUALITY, BUSINESS AND TECHNOLOGY (IJSSBT), Vol. 2, No.1, November 2013 ISSN (Print) 2277—7261 Transient Overvoltages in Power System 1 V.S. Pawar, 2 S.M. Shembekar 1Associate Professor, Electrical Engineering Department,SSBT‘s COET, Bambhori, Jalgaon 2Assistant Professor, Electrical Engineering Department, SSBT‘s COET, Bambhori, Jalgaon Abstract. equipments. This also helps us to classify type There are many reasons for over voltages in of problems so that further analysis and power system. The overvoltage causes number protection can be accomplished in the system. of effect in the power system. It may cause insulation failure of the equipments, Index Terms:-Power frequency over voltages, malfunction of the equipments. Overvoltage Switching over voltages, lightning over voltages, can cause damage to components connected to Sources of Transient Over voltages the power supply and lead to insulation failure, damage to electronic components, heating, Power Frequency Overvoltages. flashovers, etc. Over voltages occur in a system when the system voltage rises over 110% of the The magnitude of power frequency overvoltages nominal rated voltage. Overvoltage can be is typically low compared to switching or caused by a number of reasons, sudden lightning overvoltages. Specifically, for most reduction in loads, switching of transient loads, causes of these types of overvoltage, the lightning strikes, failure of control equipment magnitude may be few percent to 50% above the such as voltage regulators, neutral nominal operating voltage. However, they play an displacement,. Overvoltage can cause damage important role in the application of overvoltage to components connected to the power supply protection devices. The reason is that modern and lead to insulation failure, damage to overvoltage protection devices are not capable of electronic components, heating, flashovers, etc.
    [Show full text]
  • The Basics of Surge Protection the Basics of Surge
    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 Sweden Estonia Latvia of water supply, power transmission and Denmark Lithuania Ireland Belarus Netherlands Poland United Kingdom Blomberg, Germany Russia Canada Belgium distribution, and the transportation Luxembourg Czech Republic France Austria Slovakia Ukraine Kazakhstan Switzerland Hungary Slovenia Croatia Romania South Korea USA Bosnia and Serbia Spain Italy Herzegovina infrastructure. Kosovo Bulgaria Georgia Japan Montenegro Portugal Azerbaijan Macedonia Turkey China Greece Tunisia Lebanon Iraq Morocco Cyprus Pakistan Taiwan Israel Kuwait Bangladesh Mexico Algeria Jordan Bahrain India
    [Show full text]
  • For a Better View Staff
    FOR A BETTER VIEW STAFF presidente servizio transfer sezione maremetraggio Chiara Valenti Omero Trieste Chauffeured Service, a cura di Chiara Valenti Omero RGrent con la collaborazione di segreteria amministrativa Daniela Crismani, Francesco Martina Parenzan presentazione serate Ruzzier Zita Fusco segreteria organizzativa giuria del premio Oltre il Muro Lisa Lombardini servizio fotografico coordinamento di Davide del Nika Furlani, Jorge Muchut Degan, Ivan Gergolet, Chiara movimento copie e ricerca film Valenti Omero David McConnell, realizzazione premi Vittoria Rusalen Plexistar sezione nuove impronte a cura di Beatrice Fiorentino ufficio ospitalità immagine del festival Vittoria Rusalen Francesco Paolo Cappellotto sezione sweets4kids a cura di Tommaso Gregori ufficio stampa sigla coordinamento di Raffaella Moira Cussigh, Daniela Sartogo Francesco Paolo Cappellotto, Canci Francesco Ruzzier diario di bordo on line shorts goes hungary a cura di Riccardo Visintin stagista a cura di Tiziana Ciancetta, David McConnell Patrizia “Pepi” Gioffrè, Luca catalogo Luisa a cura di David McConnell, responsabile volontari Vittoria Rusalen Lisa Lombardini fatti un film! laboratorio di con la collaborazione di Diego videomaking per bambini e traduzioni Malabotti ragazzi BusinessFirst Trieste, David a cura di Francesco Filippi McConnell volontari Emanuele Biasiol, Emilia realmente liberi grafica coordinata, layout Burgio, Claudia Cera, Gabriella a cura di Andrea Segre catalogo e programma di sala Corrado, Andrea De Marco, coordinamento di Maurizio di Francesco
    [Show full text]
  • Volume 2 Hazard Inventory (R)
    2018 HENNEPIN COUNTY MULTI-JURISDICTIONAL HAZARD MITIGATION PLAN Volume 2 Hazard Inventory (R) 01 February 2018 1 2018 Hennepin County Multi-Jurisdictional Hazard Mitigation Plan Volume 2- Hazard Inventory THIS PAGE WAS INTENTIONALLY LEFT BLANK 2 Hennepin County Multi-Jurisdictional Hazard Mitigation Plan Volume 2- Hazard Inventory TABLE OF CONTENTS- VOLUME 2 TABLE OF CONTENTS ........................................................................................................................ 3 SECTION 1: HAZARD CATEGORIES AND INCLUSIONS ...................................................................... 5 1.1. RISK ASSESSMENT PROCESS ........................................................................................................... 5 1.2. FEMA RISK ASSESSMENT TOOL LIMITATIONS ............................................................................... 5 1.3. JUSTIFICATION OF HAZARD INCLUSION ......................................................................................... 6 SECTION 2: DISASTER DECLARATION HISTORY AND RECENT TRENDS............................................. 11 2.1. DISASTER DECLARATION HISTORY ................................................................................................ 11 SECTION 3: CLIMATE ADAPTATION CONSIDERATIONS ................................................................... 13 3.1. CLIMATE ADAPTATION .................................................................................................................. 13 3.2. HENNEPIN WEST MESONET .........................................................................................................
    [Show full text]
  • AUMOV® & LV Ultramov™ Varistor Design Guide for DC & Automotive Applications
    AUMOV® & LV UltraMOV™ Varistor Design Guide for DC & Automotive Applications High Surge Current Varistors Design Guide for Automotive AUMOV® Varistor & LV UltraMOV™ Varistor Series Table of Contents Page About the AUMOV® Varistor Series 3-4 About the LV UltraMOV™ Series Varistor 5-6 Varistor Basic 6 Terminology Used in Varistor Specifications 7 Automotive MOV Background and Application Examples 8-10 LV UltraMOV™ Varistor Application Examples 11- 12 How to Select a Low Voltage DC MOV 13-15 Transient Suppression Techniques 16-17 Introduction to Metal Oxide Varistors (MOVs) 18 Series and Parallel Operation of Varistors 19-20 AUMOV® Varistor Series Specifications and Part Number Cross-References 21-22 LV UltraMOV™ Series Specifications and Part Number Cross-References 23-26 Legal Disclaimers 27 © 2015 Littelfuse, Inc. Specifications descriptions and illustrative material in this literature are as accurate as known at the time of publication, but are subject to changes without notice. Visit littelfuse.com for more information. DC Application Varistor Design Guide About the AUMOV® Varistor Series About the AUMOV® Varistor Series The AUMOV® Varistor Series is designed for circuit protection in low voltage (12VDC, 24VDC and 42VDC) automotive systems. This series is available in five disc sizes with radial leads with a choice of epoxy or phenolic coatings. The Automotive MOV Varistor is AEC-Q200 (Table 10) compliant. It offers robust load dump, jump start, and peak surge current ratings, as well as high energy absorption capabilities. These devices
    [Show full text]
  • Varistors: Ideal Solution to Surge Protection
    Varistors: Ideal Solution to Surge Protection By Bruno van Beneden, Vishay BCcomponents, Malvern, Pa. If you’re looking for a surge protection device that delivers high levels of performance while address- ing pressures to reduce product size and compo- nent count, then voltage dependent resistor or varistor technologies might be the ideal solution. ew regulations concerning surge protection limit the voltage to a defined level. The crowbar group in- are forcing engineers to look for solutions cludes devices triggered by the breakdown of a gas or in- that allow such protection to be incorpo- sulating layer, such as air gap protectors, carbon block de- rated at minimal cost penalty, particularly tectors, gas discharge tubes (GDTs), or break over diodes in cost-sensitive consumer products. In the (BODs), or by the turn-on of a thyristor; these include automotiveN sector, surge protection is also a growing ne- overvoltage triggered SCRs and surgectors. cessity—thanks to the rapid growth of electronic content One advantage of the crowbar-type device is that its very in even the most basic production cars combined with the low impedance allows a high current to pass without dissi- acknowledged problems of relatively unstable supply volt- pating a considerable amount of energy within the protec- age and interference from the vehicle’s ignition system. tor. On the other hand, there’s a finite volt-time response Another growing market for surge protection is in the as the device switches or transitions to its breakdown mode, telecom sector, where continuously increasing intelligence during which the load may be exposed to damaging over- in exchanges and throughout the networks leads to greater voltage.
    [Show full text]