TRANQUELL Surge Arresters - kaysi.net

1 GE ArrestersTRANQUELL Surge ArrestersProduct Selection & Application GuidegGE Surge ArrestersTable of ContentsGE Surge performance and reliability oftoday's electric power system can be en-hanced with the unique characteristics of GETRANQUELL arrester products. Sinceintroducing the world's first metal oxidearrester in 1976, offering new concepts insurge arrester design and application, GEhas developed and applied metal oxidetechnology for a variety of traditional andspecial applications. GE offers one of themost complete lines of Surge arrester prod-ucts in the world today; EHV Arresters up to612 kV rating as well as high energy varis-tors for series capacitor with the state-of-the-art worldclass disk technology, all the way through theISO 9001 approved design, assemble andtest processes, GE offers extremely reliablearrester and power systems engineerswork closely to optimize product perfor-mance on the system.

2 This tradition hasmade GE the world's leading supplier ofmetal oxide Arresters and specialty GE arrester provides both excellentprotective characteristics and temporaryovervoltage capability. The gapless construc-tion provides a design which is simple andreliable while remaining Polymer and porcelain arrest-ers are designed to meet the most demand-ing service ..4 arrester Rating Selection Application Guide .. 5 arrester Service Conditions and OtherConsiderations ..9 Insulation Coordination ..11 arrester Modeling ..13 Extra High Voltage arrester Detailed Specifications:Polymer Station arrester ..16 Polymer Intermediate arrester ..18 Polymer Heavy arrester ..19 Heavy Duty Distribution Pole arrester .

3 21 Polymer Normal Duty Distribution Applications of TRANQUELL Metal OxideTechnology ..23 References ..24 Figure 1. TRANQUELL Porcelain Station ArrestergGE Surge ArrestersPage 4 2001 General Electric TRANQUELL Arresters are designedand tested in accordance with and IEC 99-4[2,3]. The standardTRANQUELL arrester consists of a stackof metal oxide disks mounted in a sealedhousing. Each disk is wedged in place of-fering protection against physical damageduring shipment and installation. On theend faces of each disk, a conducting surfaceis applied to assure proper contact and uni-form current Arresters provide exceptionalovervoltage protection of major power sys-tem equipment.

4 Under normal system con-ditions, the arrester conducts less than onemilliampere. When a Surge reaches the ar-rester, the arrester conducts only the currentnecessary to limit the overvoltage. As a re-sult, TRANQUELL Arresters absorb mini-mum energy to protect equipment Oxide DisksMetal oxide valve elements are composedof a specially formulated compound of zincoxide and small amounts of other selectedmetal oxides. These ingredients are mixedin powdered form, pressed to form a disk,and fired at high temperatures, resulting ina dense polycrystalline basic molecular structure is a matrix ofhighly conductive zinc oxide grains sur-rounded by resistive intergranular layers ofmetal oxide elements. Under electricalstress, the intergranular layers conduct, re-sulting in a highly nonlinear example, a change of arrester current of100,000 to 1 ( to 10,000A) results in avoltage change of only 54 percent.

5 Metaloxide elements in TRANQUELL arrestersmaintain stable characteristics. Acceleratedlife tests show that arrester losses will notincrease during an arrester 's service lifewhen exposed to a continuous steady-statevoltage. Stable metal oxide characteristicsenable TRANQUELL Arresters to maintaintheir low protective characteristics. As aresult, equipment protection is never oxide valve elements inTRANQUELL Arresters maintain a verystable characteristic. Accelerated aging testsshow that the arrester power losses will notincrease during its service life when ex-posed to continuous operating voltage inany type of environment. Stable metal ox-ide disk characteristics enableTRANQUELL Arresters to maintain theirlow protective characteristics.

6 As a result,equipment protection is never CollaringThe collaring system used on GE varistordisks, has a dual purpose:1) To provide an insulating collar to preventflashover at high ) To prevent the disk watts from increasingduring aging from surface oxygen GE high dielectric insulating collar sys-tem is a nonporous, non-lead ceramic crys-talline that completely seals the circumfer-ence of the disk preventing any oxygendepletion from the zinc oxide grains. Thissystem insures the varistor disk will have astable aging characteristic in any surround-ing atmosphere; gas, liquid or solid. Manycollar systems can provide the insulationwithstand to prevent flashover at high cur-rents but only a nonporous inorganic mate-rial can insure long term stable aging Construction Polymer Surge ArrestersGE TRANQUELL polymer Surge Arresters areconstructed utilizing a rugged field-provensilicone alloy housing placed over aunique high-strength fiberglass wovenassembly of stacked metal oxide order to prevent moisture ingression,the air space between the housing andfiberglass housing is filled with a hydro-phobic dielectric grease.

7 As additionalprotection, the cast metal end fittings ofthe Arresters are tightly sealed around thepolymer housing. This state-of-the-artassembly yields an arrester that is strongerand more rugged than any polymer arresterin the industry. Along with unrivaled mechanical strength,GE TRANQUELL polymer Arresters offer ex-ceptional electrical characteristics such aslow protective levels, high energy handlingcapability, and improved TOV electrical performance of the polymerarresters is enhanced by its ability to eas-ily transfer heat from the metal oxide ele-ments to the outside environment. Thisdesign is far superior to the restricted airconvection utilized in other porcelain EHV ArresterTRANQUELL EHV Arresters incorporatea heat transfer system utilizing silicone-rub-ber material wedged between the metal ox-ide disk and internal porcelain wall.

8 Heatgenerated in the valve element from steadystate, temporary, or transient conditions istransferred through the silicone-rubber ma-terial to the porcelain housing and then dis-sipated to the outside galvanized end fitting is gasketed andcemented to the porcelain housing provid-ing a complete moisture tight seal. Thissimple and rugged construction protectsagainst internal arrester damage during ship-ment and TestingDURABILITY TESTS &QUALITY ASSURANCETRANQUELL Arresters comply with thedesign tests outlined in and IEC 99-4. They exceed therequirements for the duty-cycle test, high-current short-duration test, and the low-current long-duration test (transmissionline discharge test) with no loss in pro-tective ANSI/IEEE duty-cycle test and IECoperating duty test verify that theTRANQUELL Arresters can dissipate light-ning and switching surges while operatingat rated voltage, and thermally recover atmaximum continuous operating voltage(MCOV) of 60 C at an elevated tempera-ture.

9 In other words, the arrester can self-cool under applied voltage after absorbingtransient construction and a special shed de-sign provide excellent contamination per-formance exceeding ANSI/IEEE contami-nation test requirements. More demandingtests performed on TRANQUELL arrestersalso indicate they have an outstanding ca-pability to withstand the effects of severeexternal contamination. Factory tests areperformed on each metal oxide disk. Long-term stability tests are conducted on eachgGE Surge ArrestersPage 5 2001 General Electric objective of arrester application is toselect the lowest rated Surge arrester thatwill have a satisfactory service life on thepower system while providing adequate pro-tection of equipment insulation.

10 An arresterApplication Guide for Selection of arrester Ratingof the minimum practical rating is gener-ally preferred because it provides the great-est margin of protection for the use of a higher rating increases thecapability of the arrester to survive on thepower system, but reduces the margin ofprotection it provides for a specific insula-tion level. Thus, arrester selection muststrike a balance between arrester survivaland equipment 1 lists arrester ratings that wouldnormally be applied on systems of variousline-to-line voltages. The rating of the ar-rester is defined as the rms voltage at whichthe arrester passes the duty-cycle test asdefined by the referenced standard.