High Voltage Surge Arresters Ed4

8/8/2019 High Voltage Surge Arresters Ed4

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Product programme

High Voltage Surge Arrester



ABB

Safe, secure and economic supply of electricity

– with ABB surge arresters

A new generation of overvoltage protec-tion – backed by 65 years of experienceThe ABB actory in Ludvika, Sweden is a pioneerin overvoltage protection o power equipment.Our surge arresters are the Silent Sentinels pro-tecting electrical equipment in power systemsand industries all over the world since 1938. ABB was also one o the pioneers in the introductiono gapless ZnO (metal-oxide) arresters in the lateseventies. The porcelain-housed arresters, typeEXLIM, and silicone polymer-housed arresters,type PEXLIM are the latest generation o ABBZnO arresters. Both types use the same blocksknown or their excellent energy capability andlow protection levels. PEXLIM arresters are enclo-

sed in composite housings o silicone polymerdeveloped ater years o research. While EXLIMarresters have a given place in the substation, thePEXLIM arrester range permits greater exibility in substation installations and opens new areaso application, e.g. as transmission line arrestersusing the PEXLINK concept.

Availability

Secure availability o power supply is high onthe list o user demands. Users have difculty toaccept interruptions in supply that cost them loss

o production or damage to sensitive equipmentconnected to the network. With the continuedprivatisation o the electrical industry, consu-mers can now collect steep fnes or changesuppliers with ease. Quality, both in design andmanuacture, is the essential ingredient in buil-ding reliable equipment. Correct application o our arresters ensures reliable supply with mini-mum interruptions to the consumers. Expensive“down-time” or overhaul and repairs o majorequipment is also reduced or eliminated. ABB

meets the demands o quality assurance as stipu-lated in ISO 9001. The products and the manuac-turing process also comply with ISO14000 and wecontinuously strive to reduce any negative envi-ronmental impact.

Safety

In order to protect other power equipment romdangerous overvoltages, the arresters themselves areemployed in the most exposed locations. Hence,under extreme adverse conditions, they may beoverstressed. However, our arresters are designedto ail saely and thus protect the other equipmenteven during such an event. Both the porcelain-housed and polymer-housed designs are tested

according to the stringent criteria o IEC standard60099-4 or sae short-circuit capability.

Insurance

In a typical substation, the cost o providingadequate overvoltage protection using arrestersis a very small raction o the cost o the substa-tion. This cost can easily be accepted i it is seenas an insurance premium or overall economy.Naturally, only the best insurance cover shouldbe considered.

EconomyProper selection and placement o arresters per-mits the reduction in the insulation withstandstrength o the major equipment in a station. Thiscan have a signifcant impact on reducing theoverall cost o the station. With their exceptionalprotection perormance, ABB arresters are there-ore the logical choice to protect the heavy invest-ment in other capital equipment. They make a very attractive investment that improves bothshort-term and long-term proftability.



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quickly transerredsaely outside the hou-sing by specially desig-ned pressure-relie devices. This avoids violent shattering o the housing and thusthe risk or damage tonearby equipment orinjury to personnel isextremely low.

Wide range of application

The range o EXLIM arresters is very wide.Single-column arresters are available with die-

rent rated voltages in a variety o energy ratingsrom IEC Line Discharge Class 2 to Class 5 (hig-hest as per IEC) or all the transmission voltages worldwide. Built-up o standard components, thedesigns cater to both standard and non-standardapplications.

EXLIM Porcelain housed arresters

— Our experience is your assurance

Experience

ABB ZnO arresters have been in service since1979, which speaks o our long experience withthis technology. Our arresters are in service in allclimates and conditions, including

– Cold northern countries with very lowtemperatures (-60 ˚C) and ice

– Hot deserts, with very high temperatures(+60 ˚C) and sand pollution

– Earthquake-prone areas – Coastal locations with continuous salt pollu-

tion and strong winds.

Stability and security

EXLIM arresters have a robust and stable con-

struction, well matched with that o the otherapparatus in the substation. In the unlikely event o an overstress beyond design parame-ters, EXLIM arresters ail in a sae mode. Duringsuch an event, the internal arc created by theshort-circuiting o the inner components is very

EXLIM R EXLIM Q EXLIM P EXLIM T

System voltages 2 - 170 kV 2 - 420 kV 2 - 0 kV 24 - 800 kV

Rated voltages 42 - 168 kV 42 - 420 kV 42 - 444 kV 180 - 624 kV

Nominal discharge

current (IEC)

10 kA 10 kA 20 kA 20 kA

Line discharge class Class 2 Class Class 4 Class



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6



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PEXLIM silicone housed arresters — Flexibility at its best

Building on experiencePEXLIM arresters, using the same blocks as theEXLIM arresters, match their electrical perormance.The substitution o a composite polymer materialor porcelain leads to additional advantages by way o minimised weight, exibility o erection andhighly improved pollution, seismic and short-circuitperormance.

Unique characteristicsSilicone is highly hydrophobic. This is an advan-tage in its perormance under polluted conditions – better still, any reduction in hydrophobicity under constant heavy pollution is recouped auto-matically ater the pollution episode has passed orreduced. This unique eature o silicone is madepossible via low molecular weight (LMV) silicone

oil propagating through the pollution layer to keepleakage currents low and ultimately restore suracehydrophobicity. Silicone insulators thereore requi-re little or no cleaning in service.

The PEXLIM amily o silicone-housed arresterscomes in two dierent designs: Directly mouldedand High strength (HS) tube design.

Design highlights – Directly moulded ABB employs a unique patented design to enclosethe ZnO blocks under axial pre-compression in acage ormed o fbreglass-reinorced loops fxed

between two yokes. An aramide fbre is woundover the loops resulting in an “open cage” design.

This results in high mechanical strength and excel-lent short-circuit perormance.During manuacture, each arrester module is pas-sed through a computer-controlled cleaning andpriming process beore being loaded in a vulca-nizing press wherein silicone is injected to bonddirectly to the active parts, leaving no inter¬nal voids or air spaces. The result is a complete sealalong the entire length o the arrester and henceno gaskets or sealing rings are required.

Flexibility with strengthThe low weight and slim profle permits erectionin locations where space is limited. The arresterscan be mounted at any angle, including under-hung rom the station structures or even the con-ductor themselves.

Super safetyDuring overstress conditions, the “open-cage”design permits the arc to escape directly throughthe housing at several points; eliminating the needor any pressure-relie devices. Further, since sili-cone is a very sot material compared to porcelain,there is no chance o any damage to other equip-ment even very close to the arresters. Additionally,the material is sel-extinguishing and easily ulflsthe IEC standard in this regard. Hence, PEXLIMarresters may be employed on transormer tanks

close to the bushings or on transmission towers atany point in the line without any danger.

PEXLIM R PEXLIM Q PEXLIM P

System voltages 2 - 170 kV 2 - 420 kV 2 - 420 kV

Rated voltages 42 - 192 kV 42 - 60 kV 42 - 60 kV

Nominal discharge current (IEC) 10 kA 10 kA 20 kA

Line discharge class Class 2 Class Class 4



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HS PEXLIM — High strength silicone housed arrester

Tube design for higher mechanicalstrength

In special cases with very high demands ormechanical strength, the moulded design may not provide the optimal solution, particularly at system voltages above 420 kV. Instead, whatis required is a mix between the eatures o the standard EXLIM and the moulded PEXLIMdesigns. The high strength PEXLIM tube designprovides the solution by oering comparablemechanical strength to EXLIM arresters, but

with much less mass. The seismic and pollu-tion perormance is in line with the moulded

PEXLIM arresters and thus superior to conven-tional porcelain designs.

Design highlights - HS tubeThe basic concept is the replacement o theporcelain housing used with EXLIM arresters by a fbreglass tube housing onto which the silico-ne sheds are vulcanised. The metal anges areintegrated onto the tube prior to the vulcanisingprocess. The ZnO blocks, internal arrangement,pressure-relie and sealing devices are similar tothose used or EXLIM arresters.

HS PEXLIM P HS PEXLIM T

System voltages 24 - 0 kV 24 - 800 kV

Rated voltages 180 - 444 kV 180 - 264 kV

Nominal discharge current (IEC) 20 kA 20 kA

Line discharge class Class 4 Class



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PEXLINK – Secure supply all the way

The conceptThe low weight and exibility in erection associated with PEXLIMarresters, combined with automaticdisconnecting device and suitablelinkages, opens up interesting appli-cations and is the basis o the PEXLINKTransmission Line Arrester (TLA) concept.

Lightning protection for transmissionline insulators While substations are well protected romdirect lightning by earth mats and shield wires, the transmission lines themselves haveoten been neglected in this respect. In areas

exposed to high lightning activity, this may lead to requent interruptions in the powersupply. Even with ast re-closing o linesater a ault, brie interruptions arenonetheless unwelcome to consumers with pro-cess industries or sensitive equipment.

Surge arresters connected across the insulatorsat specifc locations (e.g. high tower ooting impe-dance) along a transmission line minimize suchinterruptions and oten eliminate them altogether. While the idea is not new, it could not be realizedearlier since porcelain-housed arresters were too

heavy or easy suspension in thetowers or lines and the risk o

damage rom alling porcelain was too great.PEXLIM arresters are the ideal choice or thisapplication and the PEXLINK concept per-mits quick and automatic disconnection o overstressed arresters; eliminating the needor immediate replacement to permit line-re-energization.

Switching surge control of longtransmission lines

Long EHV lines are prone to high overvoltages along the line during switchingoperations. Traditionally, the solutions have

been higher line insulation or the use o pre-insertion resistors or the switching circuit

breakers. The modern solution, which is moreeconomical and maintenance-ree, is the use o arresters at the line ends and, where required,at other points along the line. Here too, PEXLIMarresters have obvious advantages in view o theirlow weight and exible erection as they can beattached directly to the breakers or the lines.

Further details o the above as well asother applications can be ound in catalogue1HSM9543 12-10en.



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Monitoring the health of surge arresters

Watching and waiting Well-designed and tested, ABB surge arrestersare maintenance-ree and have a long in-servicelie. Since they are sealed units, they cannot beexamined periodically (in contrast with other HV equipment) and live-line tests are difcult andexpensive – oten costing more than the arrestersthemselves. The general principle is thereore tolimit maintenance to occasional cleaning o thehousing and to estimate their condition based onservice years only.

Increasing interest or on-line monitoring o allequipment, however, has resulted in developmento some special equipment even or arresters.

Surge counter, EXCOUNT-AThe simplest monitoring equipment is a surgecounter. The mainpurpose o thisinstrument is torecord the numbero signifcant surgesthrough the arresterto which it is per-manently connected. An abnormally hig-her count o surges

in one phase as compared to the other two may indicate potential problems. However, the inor-mation may not be sufcient or making a defnitedecision regarding the need or replacement.

Resistive current is the key When a ZnO block ages or otherwise deterio-rates, the arrester’s resistive current and hencepower losses increase permanently. This resultsin an increase in the temperature, which, in turn,increases the resistive leakage current and soon until the housing can no longer dissipate theheat generated, and a so-called thermal runaway

ultimately occurs, leading to an arrester over-load. Early detection o this harmul increase may prevent a ailure and an unplanned shutdown.Hence, a good monitor should be able to detectthe arrester leakage current and isolate and mea-sure its resistive component. This may be donecontinuously or at intervals coinciding with regu-lar maintenance o the station equipment.

Monitoring system – EXCOUNT-II ABB’s advanced monitoring system, EXCOUNT-II, may be installed or direct monitoring o surgearresters while in-service and on-line.

This system comprises a sensor unit mountedon each arrester; a common hand-held trans-

ceiver unit or remote reading and sotware ordownloading and analysis o the readings. Thesensor unit is connected at the earth terminal o the arrester and is ully short-circuit proo. Itsbuilt-in power supply is charged by solar cells as well as the electric feld surrounding the arrester.The sensor unit registers not only the numbero discharges through the arrester but also notestheir amplitude and time-stamps each event. Inaddition, the total and resistive leakage currentsare able to be measured. The inormation is edby radio link rom a sae distance to the trans-

ceiver whenever called upon to do so. By usingsuitable sotware, complete records can be storedor analysis.

EXCOUNT-II can be used with any gaplessZnO arrester, irrespective o its make.



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Special solutions for high energy applications

Optimized savingsEnormous savings can be achie- ved in the design and cost o special equipment, e.g. thyristorsin the HVDC valves, capacitors inseries compensation and similar, when the arresters and varistors(multi-column high-energy ZnOblocks) are careully designed oreach special application.

Series Compensation (SC)Overvoltage protection or seriescapacitors consists primarily o alarge bank o high-energy ZnO

blocks (termed “varistors” by ABB) connectedin parallel with the capacitors. For both externaland internal aults, the varistors must maintainthe desired protection levels across the capaci-tors by shunting and absorbing a large amounto energy. It is sometimes uneconomic to designthe varistors or every possible ault condition. Insuch cases, the varistors themselves are protectedby parallel-connected spark gaps. When a pre-setlevel o energy has been absorbed or when theset temperature o the varistors is exceeded, the varistors are bi-passed by orced triggering o spe-

cially designed outdoor-type spark gaps. Since thegaps are not sel-extinguishing, the current in thearc is interrupted by parallel-connected rapid-clo-sing contacts o a specially designed breaker. ABBmanuacturers all the required components orovervoltage protection in close co-operation withthe supplier o the compensation scheme.

Special standards govern the design and testingo components or this application and a highdegree o specialized competence is required.

Energy varistors, MXEDepending on the desired protectionlevels, temporary overvoltage con-ditions and the energy absorptioncapability, the varistors are built upo multiple columns o series-con-nected ZnO blocks. ABB has thetechnique and the experience tomanuacture such varistors. The ener-gy impulses have a high-requency component, leading to increasedstress on the blocks and the housings which must be taken into account inthe design o the varistors.

Varistors may be housed in por-

celain or polymer. The ormer has the advan-tage o accommodating multiple columns ineach housing. The latter has the advantage o exible and easy erection combined with com-pactness and low weight in the orm o rack-assembly. This alternative has a great advantage when expensive EHV insulated platorms are tobe designed or accommodating them. Varistors with a single-impulse energy up to 140 MJ havebeen delivered.

Static Var Compensation (SVC)

SVC schemes oten require arresters withenergy capability exceeding that provided by a single ZnO column. However, they are muchsmaller than those or SC schemes. Standardsurge arresters (EXLIM and PEXLIM) are easily adapted to cope with these requirements.

High Voltage Direct Current (HVDC)The electrical stresses in a HVDC scheme rangerom sinusoidal stresses at power requency (standard AC equipment) to complex stresses athigh requencies (AC and DC flters) to unidi-rectional stresses (DC equipment). Special carehas to be taken when dimensioning the blocksand the arresters to account or the dierenteects o these stresses. Blocks or normal ACapplications are unsuitable or DC application.

The energy stresses can be substantial andmust be taken into special consideration duringthe design to ensure adequate energy capability and current sharing. Arresters or HVDC sche-mes are specially designed and tested in accor-dance with CIGRÉ recommendations, which areuniversally accepted.



Expanding frontiers with continuous research and development

One step ahead of the competition ABB in Ludvika welcomes the challenges o newdesigns and applications and has always been atthe oreront in arrester technology. This is possiblethanks to our teams o dedicated technical sta,good management, allocation o large resourcesand the presence o three internationally recogni-sed laboratories within walking distance rom eachother. We also have the good ortune to be actively associated with internationally reputed utilities intheir search or better material and perormance.

Technical facilitiesTwo specially designed and equipped laboratoriesor ZnO material testing and or perorming elec-

trical tests on ZnO blocks are at the heart o ourinnovative and quality products. The ormer is alsoa pilot plant where new processes and recipes canbe trialled ull scale beore being released to pro-

duction. The latter hasall the special equipmentor running the testsand is, in act, betterequipped in this regardthan most independentlaboratories. There arethree large, well-equip-

ped and independentlaboratories (STRI, ABBHigh Voltage Laboratory

and ABB High Power Laboratory) within walkingdistance rom the manuacturing plant in Ludvika.This permits us to thoroughly and continuously testour designs and products.

Where needed, we employ other large inde-pendent laboratories like KEMA (Netherlands),CESI (Italy), IREQ (Canada), etc. All these labora-tories are equipped with the most modern equip-ment or the purpose at hand.

ZnO blocks, the heart of all operationsThe most important component or the arresters(and varistors) is the ZnO block. The sizes o blocks are matched to the demands or dierentline discharge (energy) classes as per IEC 60099-4 and ABB is one o the very ew manuacturersto develop and manuacture class 5 blocks.Strong ocus on quality, rom raw material untilfnished ZnO blocks, ensure that they survivethe designed stresses with ease and with good

margins. Dierent dimensions permita large variety o standard arresters as well as client-specifc solutions withregards protection levels and energy capability. Continuousbasic and appliedresearch is carriedout in our labora-tories with a viewto improvement o energy capability,impulse-current,protective levels,mechanical strength, etc. At the same time, research in

process techniques, coupled with intensive monitoring andrequent tests during produc-tion, ensures both reducedthroughput times and rejects.

Resources ABB re-invests a very highpercentage o its turnover inR&D. Our technical sta takean active role in InternationalStandards work and our

designs are oten tested tomeet orthcoming standards where they are deemed morestringent. This is an addedbeneft to the user since hecan be confdent that thearrester purchased today willalso likely ulfl orthcomingrequirements.

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NOTE: ABB Power Technologies AB is working continuously to improve the products.

We therefore reserve the right to change designs, dimensions and data without prior notice.

ABB Power TechnologiesHigh Voltage Products771 80 LUDVIKA

Tel: +46 (0)240 78 20 00Fax: +46 (0)240 78 6 0

E-post: [email protected]: www.abb.cm/arrestersonline

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High Voltage Surge Arresters Ed4

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