Surge Arresters - CG

1 Surge ArrestersBusiness EdgeSurge ArrestersBusiness EdgeThe Switchgear Works of Crompton Greaves is located on a 1,32,540 plot inNashik on the Mumbai Agra National Highway and is demarcated in four main divisions:EHV SF6 Gas Switchgear, EHV Instrument Transformer, Medium Voltage VacuumSwitchgear and Surge Arresters . Operations commenced in 1980 with the manufactureof Medium Voltage Switchgear, which was relocated from Kanjur Mumbai specialised Business Unit spearheads the export thrust for in-house products as wellas carefully out-sourced synergestic products for supply to Trade, Industry, OEMs andPower regional establishments throughout India have factory-trained personnel to provideprompt after sales service, supporting our service personnel located at the LeadershipToday, Crompton Greaves is well on its way tobecoming a Global Leader in the field ofTransmission & Distribution.

2 In May 2005,CROMPTON GREAVES acquired the entirePauwels Group, a leading transformermanufacturer in Europe. With this acquisition, ithas become one of the top 10 transformermanufacturers in the world. To further augment itsposition in the Transmission & Distribution sector,CROMPTON GREAVES has recently acquiredtwo Hungarian companies. Ganz Transelektro,engaged in manufacture of EHV Transformers, GasInsulated Switchgear, rotating machines andGanz Transverticum, involved in the projectbusiness & specializing in high-end engineering& substation the latest acquisition, the turnover ofCROMPTON GREAVES has crossed the US$ 2billion mark; making it the first truly Indianmultinational.

3 CROMPTON GREAVES hasmanufacturing facilities on all five continentsspanning - India, Belgium, Ireland, USA, Canada,Indonesia, Hungary. International businesstoday accounts for over 50% of the Greaves already possesses thedistinction of producing world-class, qualityproducts that are globally competitive. Theacquisition has given CROMPTON GREAVES access to new technologies 765kV transformers,GIS upto 300kV. The integration process nowunderway will strengthen the technologicalcapability of CROMPTON GREAVES and itssubsidiaries and allow the CROMPTON GREAVES group to emerge as leader at the cutting edgeof Transmission & Distribution business on aglobal House, MumbaiSurge ArrestersIntroductionIntroductionCompone nts in any power system face in service, overvoltagesthat arise either due to natural lightning or inevitable Arresters are used to protect power system installationsand equipment against Lightning Overvoltages, Switching Surges Arresters are connected across the equipment to beprotected.

4 Typically between phase and earth for three metal oxide Surge Arresters consist of active part, which is aseries of highly nonlinear ceramic resistors made essentially ofZinc Oxide. Fine Zinc Oxide crystals are surrounded by other metaloxides (additives).Special Features Unique doughnut construction of ZnO elements offer highenergy capability, provide uniform density and temperaturedistribution Shatter proof performance Simple, robust construction of Arresters Extremely high non-linearity of ZnO elements Positive locking of Zinc Oxide elements Low power loss resulting in enhanced performance atelevated temperatures Controlled environment assembly line Ultra stable elements resulting in enhanced overvoltageprotection capacity Available in Brown & ANSI-Grey PorcelainsAll CG Arresters in this Catalog are designed in line with therequirements of ANSI-IEEE Standard & IEC : CG Ltd.

5 Reserves the right to change Design andspecifications in this catalogue without notice, due to continuousproduct Spares : Surge Counter, Insulating Base & Support Structure. Surge arrester Assembly Fig. 1 Grain Structure of ZnO BlockA = Bottom linear part (ohmic region)B = nee Point (breakdown point)C = Non-linear part (uptum region)D = Upper linear part (uptum region)E = Working point (continuously applied voltage) Fig. 2 Voltage / Current Characteristics ! "Fig. 3 Various types of ZnO elementsExplanation of Terms Voltage Rating :The voltage rating of an arrester is that voltage which can be appliedfor a limited time after the arrester has absorbed a large amount ofenergy as established in the operating duty tests.

6 The rated voltage isused as a reference parameter for the specification of operatingcharacteristics. Maximum Continuous Operating Voltage (MCOV) :The MCOV is the maximum permissible rms value of power frequencyvoltage that may be applied continuously between the terminals ofthe arrester . Temporary Overvoltage Capability :An arrester must be selected with a high enough voltage rating towithstand temporary overvoltages which might be caused by variousoccurrences on the system. The most common event causing atemporary overvoltage is a single line to ground fault. For aneffectively grounded system such faults will normally be cleared inless than one second. Therefore an overvoltage capability based ona duration of one second is usually recommended.

7 Also, the belowtable shows Temporary Overvoltage Capability for a time range to 1,000 Voltage RatingsThe chart below indicates the minimum MCOV customers need to specifyfor an arrester as a function of system minimum recommended ratings for solidly grounded systems allowfor a temporary voltage rise of at least 40% over a period of one temporary overvoltages may require higher VoltageTOV per unitPeriodof MCOV with(in sec)prior of CG Surge ArrestersSurge ArrestersSurge ArrestersArrester Application InformationCG Arresters are designed to use at altitudes of 1000 M. Arresterscan be customized to meet requirements for higher altitudes. CGarresters can be used at an average temperature of 40 C & wheredaily maximum temperature does not exceed 60 degC (140 F).

8 Theenergy absorption capability a two shot energy discharge withinone minute, signifies the switching Surge capability of these Grading Ring is a requirement, it is dispatched along withthe base mounting & Terminal options can be customized tospecific needs in addition to the options provided in this Counters to monitor arrester discharges are available withbuilt in milli-ammeters. Where Surge Counters is a requirement, it issupplied with suitable Insulating bases (IBs) for arrester isolationfrom earth. All Arresters are identified with a unique serial number;multi-stack Arresters have unit name-plates indicating position ofthe unit in the column. arrester name-plates have information onthe rated voltages, MCOV, Pressure relief current, serial number, etc.

9 CG Arresters can be customized to meet virtually all the duty cyclevoltage (Voltage Rating) & MCOV Cleaning ArrangementBasics of CG Surge ArrestersSurge arrester Selection ProcessSurge ArrestersSR. PARAMETERSSURGE arrester PARAMETERS1 System VoltageRated Voltage Maximum Continuous Operating Voltage (MCOV)2 Maximum System VoltageRated Voltage Maximum Continuous Operating Voltage (MCOV)3 System EarthingRated Voltage Maximum Continuous Operating Voltage (MCOV)4 Basic Insulation levels (LI, SI)Residual Voltage (LI, SI)5 Line length, Energy involvedLine discharge class6 Short Circuit levelPressure relief class7 System over-voltagesTemporary over-voltages8 Pollution levelCreepage distance9 AltitudeArcing distance, CreepageWith available Surge arrester parameters and from appropriate table, other ratings of Surge arrester can bedetermined.

10 The tables show typical requirements from customers. Surge arrester with different parameters canalso be ArrestersDistribution Class - Normal DutyReference Standard-IEC 60099-4, ANSI IEEE Std , IS 3070 (Part-3) arrester Type & Class-Gapless, Distribution classRated FrequencyHz48-62 HzLine Discharge Class-75A, 1000 micro-secNominal Discharge CurrentkAp5 Energy Handling CapabilitykJ / kV of Leakage current at MCOVR esistive (Max.)micro-amps150 Capacitive (Max.) micro-amps600 Product to 36 Impulse RV atLightning Impulse RV (8/20 micro-sec) atCreepageOverallRef. (1/ 2microsec)distance mm Height (H) * Diagram not to 36kV Dist. Class SA(Normal Duty) Reference Standard-IEC 60099-4, ANSI IEEE Std , IS 3070(Part-3) arrester Type & Class-Gapless, Distribution classRated FrequencyHz48-62 HzLine Discharge Class-125A, 2000 micro-secNominal Discharge CurrentkAp10 Energy Handling CapabilitykJ / kV of Leakage current at MCOVR esistive (Max.)