High Voltage Surge Arresters Buyer´s Guide ABB Surge Arresters — Buyer’s Guide Edition 6, 2008-08 1 Contents Table of contents SECTION-PAGE Product Introduction A-2 Information Definitions B-1 Simplified selection procedure C-1 Design features - Porcelain-housed D-1 surge arresters, EXLIM Design features - Silicone polymer-housed E-1 surge arresters, PEXLIM The PEXLINK concept F-1 Quality control and testing G-1 Technical Zinc oxide surge arresters with silicone polymer-housed insulator: Information PEXLIM R, IEC class 2 H-1 PEXLIM Q, IEC class 3 I-1 PEXLIM P, IEC class 4 J-1 HS PEXLIM P-T, IEC class 4 K-1 HS PEXLIM T-T, IEC class 5 L-1 Zinc oxide surge arresters with porcelain-housed insulator: EXLIM R, IEC class 2 M-1 EXLIM Q-E, IEC class 3 N-1 EXLIM Q-D, IEC class 3 O-1 EXLIM P, IEC class 4 P-1 EXLIM T, IEC class 5 Q-1 Accessories: Introduction R-1 Condition monitoring R-2 Design R-3 EXCOUNT-A R-5 EXCOUNT-I R-7 EXCOUNT-II R-9 Other Purchase order S-1 Index T-1 Customer notes U-3 A-1 Edition 6, 2008-08 ABB Surge Arresters — Buyer’s Guide Introduction Safe, secure and economic supply of electricity — with ABB surge arresters ABB surge arresters are the primary arresters survive the designed stresses protection against atmospheric and with ease and with good margins. Dif- switching overvoltages. They are ferent dimensions permit a large variety generally connected in parallel with the of standard arresters as well as client- equipment to be protected to divert specific solutions as regards protection the surge current. The active elements levels and energy capability. (ZnO-blocks) of ABB surge arresters are This Buyer’s Guide deals with high manufactured using a highly non-linear voltage surge arresters for standard ceramic resistor material composed AC applications. For other applica- primarily of zinc oxide mixed with other tions, such as series capacitors prote- metal oxides and sintered together. tion, shunt capacitor protection or DC Strong focus on quality at all stages, applications, contact your ABB sales from raw material through to finished representative. product, ensures that ABB surge Product range Product family Arrester Type Max. system Rated Energy Mechanical classification 1) voltage 2) voltage 2) requirement/ strength 3) Lightning intensity Um Ur kVrms kVrms Nm PEXLIM — Silicone polymer-housed 10 kA, IEC class 2 PEXLIM R 24 - 170 18 - 144 Moderate 1 600 arresters Superior where low weight, reduced 10 kA, IEC class 3 PEXLIM Q 52 - 420 42 - 360 High 4 000 clearances, flexible mounting, non-fragility and additional personnel 20 kA, IEC class 4 PEXLIM P 52 - 420 42 - 360 Very high 4 000 safety is required Major component for PEXLINKTM concept for transmission line protection. HS PEXLIM - High strength silicone 20 kA, IEC class 4 HS PEXLIM P 245 - 550 180 - 444 Very high 28 000 polymer-housed arresters. Specially suited to extreme seismic 20 kA, IEC class 5 HS PEXLIM T 245 - 800 180 - 612 Very high 28 000 zones. EXLIM — Porcelain-housed arrester 10 kA, IEC class 2 EXLIM R 52 - 170 42 - 168 Moderate 7 500 10 kA, IEC class 3 EXLIM Q-E 52 - 245 42 - 228 High 7 500 10 kA, IEC class 3 EXLIM Q-D 170 - 420 132 - 420 High 18 000 20 kA, IEC class 4 EXLIM P 52 - 550 42 - 444 Very high 18 000 20 kA, IEC class 5 EXLIM T 245 - 800 180 - 624 Very high 18 000 1) Arrester classification according to IEC 60099-4 (nominal discharge current, line discharge class). 2) Arresters with lower or higher voltages may be available on request for special applications. 3) Specified short-term service load (SSL). ABB Surge Arresters — Buyer’s Guide Edition 6, 2008-08 A-2 Definitions Definitions Note: The standards referred to here- ANSI (MCOV) under are the latest editions of IEC ANSI lists the maximum continuous 60099-4 and ANSI/ IEEE C62.11 operating voltage (MCOV) for all arrester ratings used in a table. The value is used Maximum system voltage (Um) in all tests specified by ANSI. MCOV is The maximum voltage between phases less stringent as regards uneven voltage during normal service. distribution in an arrester. Nominal discharge current (IEC) Temporary overvoltages (TOV) The peak value of the lightning current Temporary overvoltages, as differentiated impulse which is used to classify the from surge overvoltages, are oscillatory arrester. power frequency overvoltages of relatively long duration (from a few cycles to hours). Lightning classifying current The most common form of TOV occurs (ANSI/IEEE) on the healthy phases of a system during The designated lightning current used to an earth-fault involving one or more perform the classification tests. phases. Other sources of TOV are load- rejection, energisation of unloaded lines Rated voltage (Ur) etc. An arrester fulfilling the IEC standard must The TOV capability of the arresters is withstand its rated voltage (Ur) for 10 s indicated with prior energy stress in the after being preheated to 60 °C and sub- relevant catalogues. jected to energy injection as defined in the standard. Thus, Ur shall equal at least the Residual voltage/ Discharge voltage 10-second TOV capability of an arrester. This is the peak value of the voltage that Additionally, rated voltage is used as a appears between the terminals of an reference parameter. arrester during the passage of discharge current through it. Residual voltage Note! TOV capability of EXLIM and depends on both the magnitude and PEXLIM arresters exceeds the IEC the waveform of the discharge current. requirements. The voltage/current characteristics of the arresters are given in the relevant cata- Duty-cycle voltage rating (ANSI) logues. The designated maximum permissible voltage between its terminals at which an Energy capability arrester is designed to perform its duty Standards do not explicitly define energy cycle. capability of an arrester. The only measure specified is the Line Discharge Class in Continuous operating voltage IEC. Often, this is not enough information It is the maximum permissible r.m.s. to compare different manufacturers and, power frequency voltage that may be therefore, ABB presents energy capability applied continuously between the arrester also in kJ/kV (Ur). This is done in 3 differ- terminals. This voltage is defined in differ- ent ways: ent ways (verified by different test proce- dures) in IEC and ANSI. Two impulses as per IEC clause 8.5.5. This is the energy that the arrester is sub- IEC (Uc) jected to in the switching surge operating IEC gives the manufacturer the freedom duty test (clause 8.5.5.) while remaining to decide Uc. The value is verified in the thermally stable thereafter against the operating duty test. Any uneven volt- specified TOV and cU . age distribution in the arrester shall be accounted for. B-1 Edition 6,5, 2008-082004-10 ABB Surge Arresters — Buyer’s Guide Definitions Routine test energy Note! The altitude correction factors are This is the total energy that each 13% per 1 000 m (IEC) and 10% per individual block is subjected to in our 1000 m (ANSI). production tests. All EXLIM and PEXLIM arresters fully comply Single-impulse energy with IEC and ANSI standards for installations This is the maximum permissible energy, up to 1 000 m, often with a large margin. which an arrester may be subjected to in one single impulse of 4 ms duration or Pollution performance longer and remain thermally stable against IEC 60815 defines four levels of pollution specified TOV and cU . (from light to very heavy) and stipulates the required creepage for porcelain housings as Note! Corresponding values based on indicated in the table here. Uc are obtained by multiplying the cata- logue values by the ratio Ur/Uc. Pollution level Specific creepage in mm/kV (Um) Short-circuit capability Light (L) 16 This is the ability of an arrester, in the Medium (M) 20 event of an overload due to any reason, to Heavy (H) 25 conduct the resulting system short-circuit current without violent shattering which Very Heavy (V) 31 may damage nearby equipment or injure personnel. After such an operation, the In the absence of similar standards for arrester must be replaced. polymeric housings, the table also applies at The system short-circuit current may present to such housings. be high or low depending on the system The creepage distance is the length mea- impedance and earthing conditions. sured along the housing’s external profile and Hence short-circuit capability is verified at serves as a measure of the arrester different current levels. performance in polluted environments with respect to the risk of external flashover. External insulation Since the mean diameter for all the stan- withstand strength dard arresters is less than 300 mm, the It is the maximum value of the applied specific creepage distance is the same as the voltage (of a specified wave shape) nominal creepage distance. which does not cause the flashover of an arrester. Unlike other equipment, arrest- SSL ers are designed to discharge internally Specified short-term service load. and the voltage across the housing can never exceed the protective levels. Thus, SCL the external insulation is self-protected if Specified continuous service load (for its withstand strength is higher than the PEXLIM arresters this is a declared value protective levels corrected for installation based on cyclic loading). altitude. The standards specify additional safety factors, exclusive of correction for MBL altitude, as under: Mean breaking load • IEC: 15% for short impulses and 10% for long impulses (at sea level) • ANSI: 20% for short impulses and 15% for long impulses (at sea level) ABB Surge Arresters — Buyer’s Guide Edition 6, 2008-08 B-2 Definitions Definitions — Transmission Line Arresters Backflashover Shielding Occurs when lightning strikes the tower Protection of phase conductors from structure or overhead shield wire.