Railway Electrification Power Supply

8/2/2019 Railway Electrification Power Supply

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.FAPER. No. 391

Railway EleetrUioati.o:o(POWER SUPPLY SYSTEM)

ByDR. F '. A. HAMDANI, P.R..S.~

As apart of its modern iza tion p ,rogramm e"Pak ist fl l.n Westerlil RaHway .h as emb ark ed uponfue in t lo du c~ io n.( )f 2 5 K V , Single Ph ase, A. C. Rlectri flCll~:ionon its Lahoee-Khanewal Section. extending ever ]178mi[e:s, aD i'nitio. TheP raj eel w hich . startedie June il l 96 6, is gelD ing momentum. withilie pasaa ge ofeaoh day_ WhHe the Lahore-Raiwind Section bplanned :~o,rtrial IUnsmit~a11y,a pp re he ns io ns a r, ;:e xp re ss ed o fte n by laym en as to the v h 1 . b H w t y of the Projectin .reg :afid to p ow e r supply sy s~ em d .e Jle nd en t a s . i t w ould be: an an externals ou rc e ( I,u uid e the eonteol of Railway riz'J WAPiDA supply. .FffqUtncy ,o ffailu re of ,ordIn ary lo w tension p ow e r supJ)ily in cities o r f lu c tu at io I! ls~n vo lt ag esin a lo ca ~it;y ~ s.p ,r ob ab ly t be criterion and as a basis would. perhaps jus~i(ysllc.b.misgiv.~n.gsand i n c on se qu en ce b as c au se d J : 1 e f i . e c ' t i o D s o n th e th in kin gso f many.Itmay 'be still~edat the outset that power in-feed tothe P.W.It. Electric Over-head Tra ctie ,n Sy steD l would be from the WAJP'DA H igh T ension integrated.Grid S U P ' P , l . y wh ere ln ciden ce of o utages, iu [eu up tio '.n s is rather rare and . alm ostnesHgib~.e.

P.. W. R. Electrification CeU~,hOW 'e ve r,a s, E !Il g~ ne ers aDd . WAPDA':sfJ ,rospecdv,e consumers have looked ln to every aspect of the proposed supplysy stem a sh as WArDA itse.IDfo mee t i ts r espon sibi li tl es , .Ieforepower s,ystema s it w , ou llid sta nd ultimate~y is deHneated~, it would be pertinent to ment~olnthat de~i.gill(lomidera[io1l1s, have. been a function ofthe eeenomies and maximumme basbeen made of the e xb tln g f ac ilitie s to aV(!i~dextra costs both. illl fOfelgn9ch.a:nge and loca1currency. To that extent alimit w as imposed on the planne.nlto what: could have beea catered for otherwise, Ideally P.W.R. should. haveenvisaged a sy stem of pow er generatlcn based at the Ioad centres a~(liIl.gwith th ec ou com ita nt H i gh . T en sio n 1 'r.a nsmis sio I!l.L ia es to m ee t 'both T raction reqnae ..moots as wel l as its own which couldheve been justified. if aU the isolatedpow 1er requirem ents of Railw ay from Lahore to Khanewal were; iDt~}glated. .Railway already main tains P ow e r Mo uS ies at Lahoteand Khanewal a;sat etherimportant jtm.ct~o:ns,which could be augmented and modernised bytb.e pro-viS~Oi!il0'( q\ri.c'I::.tarti:ng~ efficiient gas turbine sets at each en.d w ith the a vallabililyof ga.s.This, hewever, bes id e s , eon fl ic ti ng with WAPDA"s jurisdiction as a


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lieneee, weuldha "lie u ps e1 , th e e ce aemle s o f E ,le ctt1 fic at~ (I,II. a l'tD oilll.g b p.riliVidiogthe muchneeded velief to WAPDA~s distribut~~oft system. Another alternat~.vlewas to arrange at extra cost fora U ,2 ; KV Trensmissien Line along the Trackexclusively for Electrificat iaD" looped, into WAPDA~sGrid Stations ,enmuteso thata m ore re liable and t r c l ' l l . b E e free sy stem eeuld be guaranteed. .A U thist.hougb.very well is extravapnt. It is necessary to ca;Fefwly balance the traetionrequirements a,gainstpow er a.vaib bili ty " if most eeeacmic scheme iis to , be:designed.WA'DA~s Grid on the otber h 3 l 1 1 d . has: deve~oped ,sumc~ent~yandattained! a good measure of advancementand this reassuranee forms the basieparameters Ior the justifiea~lom of electrietrnetian. A . properly eoneeived : S Y ' 5 ~ e m ,~ or E ~ .e ctric T r ac tio n. s ho uld . b e o ne w b ich ' beside - smatins us e of existing facilities,does not thro'wex.cessive demand on . the facil~.ties 'o,btai.nm,g. It should havefe ed in g p oin ts suchtbat in . th e e ve nt of ,ou~~geo f one ofthese~the track ean befed from the adjaoent tract seetiens, 10 . ~eep:in\gwith. this~a best possihlepowe r system. fo r EI .ec tn . c 'Tracdoo services has b ee n e v,o ~,v edw h ic h is d es cr ib edin d eta H h e!l:e afte r.S ys te m ,o lH ig& 'TeMwD s .upp~y

IApn)fi~e 'of the seetioato be electrified is shown in .Fig. I. Based on

the location of ~mportantWAPDA Grid S ta ti on s , c o at ig uou s to Rai lway trac.kfrom. L ahore to K hanew al,five Track Feeder S t a t i o l D - i ' J , lila.ve been de~er.minedvi=,.~8itKotLakhpar, Wan Radha Ram, Sahjwal~M~an 'Cbannun and Khaaewal,WArDA has 132 KV Gri d. S ta ll ti o.n s a t Kat l.akhp:at and Sa]biwa~1 whi~ .e 66,KVGrid StatW,ons at M .~aD.Cha:n.nuu arnd.Khauew,at For '~app~ng 25 l{V supplyat the fiv e T rack . Feeder :Stat~ons"Rai lwaywm prov.ide, mnd e ree t cOim.plete132 / 166 KV step-dow n ~,uipme.mt. iu . W A PD A. Yar(k~ , such . as lsolaltGrs~ Trans -formers and Circuit Brealiers" exUns.~!OJll of Bays , and O!!llltries" bes:~des;puttingup' a completely new ,66,KV :Sulb-Staliom at W'an Radha Ram with p,tuvisiolllfo :r~noom ing and outgoing lcircuit Breakers fOF use and. ultimate , e x t e : r n s i o i [ l , byW APDA . :B ased om t he an tiolpa .t ed , trainoperefiag coudjd.ODS and. c o i D : s e q 1 ! J J e n l tn et- w ork a .n aly se [ studies carried o ut, the p ow e r mqu iiem elil~ s at th e vru:"ious;p ro po se d in te :[~ co nll.e eu on . p oia ss is detailed as OD n e:x tp ag e ...

The Iad ",g s o f lran sfo 'rm ers 'lo cated at each o f'lti!l.eW AP'DA G rid S tatio ns.have been. decided upon Ra1]way demand under normal and. 'o,ulage cOlJl.di t ionsand load thrown over from one feeding pointte the; other Gn.aoooun~ of emer-gency ,or failure ,of atranssermer. Sahiwlm isthe most heavily loaded. feedingpoint and wee feeds on e ithe r' s ide of Sal1 Liw a.~re ,a~ 66 K V t it was necessaryto lim it demand on thesesecdens w hile suitably ie - - inforc1l i lg Sahiwa]. Sahiwalunder outage conditions wml~d.have max~mum demand of IS MVA , ihourmaximum of M2MVAand RM.S, fipre 0;f1.1 MVA, based. OD. which 2,x.1.5 MV.t\


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PAPERNo. 392

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32 'PAPER No~ 39 2

To~a1

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LOCATION.. : ! ; Iz1. KMLathpat2. Wa:n Radha Ram3. Wan Radha Ram4. Sahiwal5.. Mmn Channum6. Khanewel

132125 XV T ea sfe rm ers bsve been provided there.K.ot Lakhpat is anmherr,e lativ e:~ y loa ded p oin t but RMS demand under wors t ecndltiees w,QuUdmotexceed 7.4 MVA (witb faUur,eofa Traasfcrmer a:1tWan A;adhaRam) whichCUD. be suitablycatered for by one Transformer of 7..5 MVA~although p,rovisionhereof enother has abo been m ade: purely as a s ta nd .1 ily w i .th 166 XV tappmg~OI use a.s a, s pa re tr;a ::n :sfrme r fo r w hole of the sys tem, F or the :rest ,of the 66K V feeding pa~.nts~ RMS demand under norm a.l and outage condi.tio11l5 is notexpected to exceed 3,(} MVAal t any time per cil,euitand. dependen.t . OD. th eeconom ics of manufacturing) 5 M V A U ni ts ha vebeen se lected and sW:1 i1da rd ized.Transfor-m er capac itie s atvarious G rid Stations provided . to m ee t 'dleR ailw ay~oladare therefore, as under r-

I.. Kot Lakhpa~, ~ 2; x 7.5 MVA , 132/25 KV (One spare Mth 66 leVTap).2, W an Radha Ram = x 5 MVA , 166/25 KV .3. Sahiw.ai, ~ 2 X 7.SMVA~ 132/25 I{V.4. M ien. C hannun. = ix.s M VA~ 661 25K _V ~5. KhanewaJ= I xS, MVA~ 6 6 J 2 5 KV.

Select ion of 7 .5 M VA Transformer for 132 XV pdmary system . and : 5M VA for 66 IC V, besides m eetingpreseat load requirem .ents eom sases suitablemar,gin for l l iolad geowth also, Pattern of power demand and Tr,Dllsform.erloading at Sahiwaland Kat Lathpat is show n in Figs . ..2 and .3..

..It ~santidpated tb3i.t\he in sUmoous mu,. deman d under w orst oo.mdidou w~ll b;:1.~ to I.5rl:!msthe 1ifiih:il.ut>eI!1a~m!;llll~eDult!dsquot(~ above.


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P~APER 'No. ,39.2P .I '.im aryEq ipmm t a od . ll'e em1 l:l: .Ara ngmne nts

Fig, 4 gives the schematic di,agf,am of the E ll J{V and 6 ,6 KV tql!dpimen:being :~nsta:Hedin the various WAP'DA Grid Sub-Stations., For 132 KY" eircu itbreaker ruprtUrli l lB ea padty of JSOOM V A has been chosen w hile for the 66 K V I'thebreaking lcapacity would be 25!OOMVA.. Br~efly the equipment bdnginstalled at the v arle us WAPDA G r.~ d $ .1 IJ il- Sw 'tlo nsWQU~.d b e as ]]I.o der:~Eol Lakhpa.t

(I) Yw o, deuble pole li32 K V " :1 500 MVA ~ 600 Amps site ratiagtype ~OSJO~, small eil voh; lme.p11 leuma~icaU.y closed, com-p ress io n :s prh 1l!_ gp en ed , eiree i t breakers w ith local and remotecOlll~r,ol served by a . c ommon. ai r , rom presserte control tw o, m ainstepdown traasf cemers,

(if) Set of two, separately mcunted current transfo1l,i 'merpo,sts foreach eireuit breaker, leach post aeeommeda tin.g :On.e current trsnsformer, ratio 1 5 1 m amp; 15 VA~ for ammeterservice and. for ovefcu:rrelll~ proltedion.~Ollie eurrent transformee ratio 751~ amp. 1 .S VAt for eestrletedearth fault protection.On e cu reen t 'tran s ofm er rati!o 1 00 /5 : am p,. 1 5 VA J< fo r ln teg ea t~d.mere.ring ~yK.WH meter with m axim um d e:m and in .dicatarp er. 'circuit.Tw o double po~e; double CM[],ie ()


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PAPER No. 3~92 31One;eurremtransformer ratie 3001:5~amp.of suitable output andaccuracy for 2 stage distance protection.One current transformer ratio 3O O n O C i l I S~amp. 15 MVA eutpu tfor ammeter service and back-up overcurrent protection.

(iii) Two, 2 phase, 66 KV" 600 ampere, 2500 MVA, type iOSM.4~~,outdoor pattern circuit breakers) each to centrol one uruailll step-down power transformer.

(l~)One set of two separately mounted current transformer posts foreach of the above circuitbreakers, e;a,c]l pcstaceemmod ating :-One current transformer ratio mOO/I-amp".- m s VA~ forammetcrservice and overeurrent protecsion,O ne current transformer ratio 1OO ' /l',am p. IS VA fo r fie stric te de arth fa ult p ro te ctio n.One cunent transformer rasio lOG/I-amp. . 15 VA output fa tintegrated metering by KWH /M3X~m lL l.m d em an d meter percircuit,

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(v ) One set of 66 K.V bola.ting Switches consisting of:-Two, Triple pole 66 KV,. 600 amp. line Isolators each with singleearth switches, forcontrol of th e incoming grid. feeders,Two, Triple po[e 66 KV~ 600 ampbusbar Isclateresuitable foreonrrol of '[be busbar side of the 66 KV eireui t breaker eatlreincoming grid feeders.Two, double p o , l l i e , 66 KV~ 600 amp, busbar lso.laton for th e5 MV A, fj61 25 K V" transformer cin::ui til.

(vi) One se t of galvanised steel structures, consisting of ~-Four High-level structures fortwo 66 KV triple pole;line isolatorsand. twe 66 KV busbar isoletors ..Tw o structures fo il' tw o do u ble po le 6 ,6 K V isola tors fGil' th e trans-former circuits ..

:j!~One set of three, busbar connected, 66 XV volt,age transfonners,output 200 VA per phase.

(vii) Tw o 5 > MVA , 6 6{ 25 KV , sin gle p ba se )SO c is , QU immer,se d" n atu ra l-Iy eooled outdoor pattern, core type, main stepdewn poweru.!.li.lilsformers, complete with all necessary CiU:rre:ntntl!lsformers"protection equipment and. nUings w.~thmounted surge; divertors ..

Theeqnipments at this station would be idenncatw that imstaUed. atKat Lakhpat except that the stepdown transfcsmers wou~d be both 132/2$K, apart from feeding arrangements. and. bnsbar coanections,


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:3 8 PAPER No. 3 9 . 2M:i8!D CbaUQUD.

0) One, Two phase~ , 6 6 XV, 600 ampere site rating, 2500 MVAbreaking capacity, type ~OSM.Hf~oub:loor pattern sman oil.volume circuit br-eaker. complete with a motor charged, springclosing, compression spiring: openingmecba:nism. The ci[cuitbreaker would hesui~.ab.~efOI localand for remote control,

(ii) Two separately mounted current tranSfo.rm.elposts.~ea.cb.postaeeom medatasg :-One current t ransformer ratio lOO/l - :a .mpere, i:; VA output, forammeter service and .for overcurrentpruteeticn.One currenttransfcrmer ratio 10011~ampe[e~5 VA output, forrestricted earth faultprotection.One current transformer ratio lOO.fI-a~m.Jlere. 15 VA output, forimtegra,tedmetering by KWHIMD meter p~i circuit.One double pole, 66 K.V" 600 ampere busbar isoblt()ilt'.

"iii} One, S MVA~ ,66/25 ICV,. sjng~epbase,~ 50 c I s . o n immersed,ml,l'turaUyeeeled, outdoor pattern, core type, malo stepdownpowell transformer, complete with 3 . 1 1 1necessary c u r r e I l l trans-formers, protection equipment and fittings with mounted surgediverton.

The circuit b:r:eake:rs.~urrent transformer posts and. isolating switcheswouM have their own supporting, ga~vamsed.steel frameworks.Kbau:ewal

The equipment at this station. W O t J! .d . be in accordance with the require-ments, to form an extension bay to an existing 6:6K.V switching stalion andwould. be generelly tbe same as fer Mian Channen described above.

In a.d.dition~o the above, auxiliary equipment viz . f>e'layand. controlpancls would be provided :a t each Grid. Sub-Station w:mch would be of theindoor pattern f o . 1 L accesnmodatien wi tbh:!l. the su b-statien control buildin gs a,The extension bays wouldbe earthed through 19/.083,~' ( o . .m Sq. Inch) copperand. connected w itil (be exjst~n.gsub-statson O O i i U l i D g as also double earth wouldbe: provided M ,aD the 1 I. T . equipment.2S KV, Oryerhal 1'r;aHmissiuo Lines

P ', W . R. w oruld also ltlro"lide fo r th e mnsta1!latiom of an . e stim .a teO to ta l , o , r" J ~ miles of sml~Jecircuit 25 KV overhead Transmiesloa Lines from variousW APDA Grid Sub-Stations to, the cont1l.ecting T rack F eeder S tali!o:n$ as detailedhefieu.nder ;~


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PAPERNo. 39'2 4 . 3f au :~ ts ,. T h e rnnge'Oir high s.ettimg: is from 400 to U X l) % ,o,fthe:: fun l o u . current w hile the low . seUing is from 1 0 0 % , to 4 0 0 ) 0% with.a . timer ()f O.l to ], sec on ds,

(iii) Su r g ,e l J iv er to r sTransformer mounted s.urge divertors of the foHowing type havebeen. provided :

(a) 2 eM 1.210or ~,32 KV .(b) BM 60 for 66 !KV.(c)B,M ,37 for 25 KV.

(While surge d i v f \W " t o . u in . thelwo, p h a s e s have been provided ODthe p'.r~marys~de"on theL V side only one surge d:iver l to[ bas beenpr'o'vided in tb e phiue and. the other phase bas been. so lid lyearthed),

(iv) Tramformet' Pro tec t ionSingle T ra nsfo rm e r 'c irc uit protection scheme is s h . O w . n . ~n fig. 7~b oth . fo r t12 KV and 66 KV sy stem s" The earU l fauU relays Elf'~are ecnnected to protect the tra:nsformer p.[imary cireui t andtheseeoadary windings. Further Ilotectw~on ispro,vid!ed by the 1 !l seo f ga :s o pera te drela ys w h ich . Is : : i l l sta nd ard de vice , o f the B uehholoztype ,gi.v.~n.gan alarm on gassing and trips, the breaker O 'D gasoroi] surging. o n and winding temperature thennometersareprovided, mounted .in a sheet steel enbieal on the side of th etransfarmer; Bothwcrk oln the Iiquid ,expansion princlple andhave vari,ab~,eala.rm ,andtr.m .p me l!c ul1 s w itc he s. Th e w i l l : u J i m g .tempera lure taermemeter has the ad!dHion .o f a hea~e:r arrangedtobias operadn,g mechanism. The hea~er'is energized by Iicurrent transfeemer in prGporti,on to the load. ontlil,e ma inht.ans ...former such thet its thermometer corresponds to the'WindiDItemperatere . The recommended se U ~:n gs fo r th e ;a .~ a:rm,amdtrlpswitches on. both thermometers based on British Standard Codeo fp ra c& ic e - arre- g~ven as under ::-Oi~Alarm 7 , s o , eSloe

1 056C115C

Temperature Trip,Winding AlarmTemperature Trip

25 KV L ine ProtectionPr'ctection for tbe 2:SKV SinBle Phase Lines and. the associaaed 25 KV

Transform ers w ould be .o f the o ,v 1e r.8 l'Ud ifie re nti,a d ty pe in itia tin g trip pin g o f th econn.ected H . V . 'Clr,cuIt Breakers, T he p irim arYGv er eurren t proteCitioD


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44 .PAPERNo~392

",!t III A I II ,I !o jI r/i,[p I'.U,(l I'lliUtr./r AUTRfC rCtJ f"llli'lj;il' F'~(j'H :R'll!.A~IG 6 .. : 5 . 5 1 1 1 1 ( : : 1 , e ~ " " 1'.U~_o/e , ( lVi I' ,I l~R IE"" t t lE U "i" f t. (M) mGW~i".T ()/l:t.t!i{,tjq~"r ,u', Ill!!'OIT ttl~ ttA4Pt R."tJRf:. ,CON ' ' ' ' ' fS !


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is, arr,anged to td p 'the breakerinstantaneously far primary faults and arlera~ujmble 'lime delay for secondary faults, the differentiatien being obtained bysettin.gs the instantaneous elemen t to a value of CUITent above the caleu Iatedsecondary fault level of the transformer. This sy stem ,a U ow s fiuUtime!cuuentgl'ading with. the track side protection while providing o"vercurrent and earthprotection fer the .25 KV Transmission Lines, where' a. low earth returnimped-ence ~.s ,0blamed. bys,oUdly connectiagthe return coad uctoete each supporttower, The setting of the earth faultrelays type 2B3 and over current relaystypeElC/IU/TCD would be determined by the 25 KV track side protection, thecurreut setung bemghigher than the equivalent, relays on the track: side equip-ment and the time lag relay settiag longer than the total opu.at~!ontime of thettllC.t side equipment plus 'the r - e s e t time of th.e over cnrrent element. Theserelays being on the primary side of the transformer wou~d.prosect agairn:st faults'below the high set over current tela y:ssetdng as well as .2S .KVtransmiss:[onIine faults, Undernermal operating conditions transformer switcb-on surgesand Railway Track faults may cause operation of the over current element:flagswff itb .o ,u t tr ipping , the H V br-eaker. In th e cue. of atri p' occurring th e timedelay :rela:ylag would operate a:nd~:hu8 indicate fa.ult on the ,sup:p~yside 0" the25 KV 'switch board,Track. Feeder Stations, aDd Track Sooti.o.ung Cabins

Depending QU. the pointso:f :supply~the considetation of the traffic 'to,behandled and the electrical charaoter.i:stic$:o,r the overhead and supply system,.an optim urn sp.~c:ing;of thetraek feeder stations is determined. For the .Lahom.Khanewal Section, however, th e pre-dcminant consideration has been the:locations of the allied Gdd Sub -S ta tio 'n s; T ra ck . F e ed er S ta tio ns , .h~v,e~ber,e$ole'jrbeen located at the site of the track. at the fonow~ng:p~ateiS ;~

(I) Kot Lakhpat,(2) Wan Radha Ram.(3) Sahiwal.(4) Mian Chanmm,(5) Khanewal,

T he d istan ce between Kot Lakhpat and Wall!]Radha Ramis .5 1 mlles,between Wan Radha Ram and Sahiw!~ 43 miles, Sahiwal an d. M ia n, C h an nu n46 miles and. Mian Channun and Khanewal 21 miles. Simultaneously SevenTracie Sectioning Cabinshave been provided along the track for thepllrposeof inter-ecnnecting a.djacent track: overhead 8[1pp]y sections UD:de-I variousconditions. whenever warranted, These track sectIoning c:abmff have been


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PAPER No..3 9 2 .

(a ) Ra iwind .(b) C h ha flm a M a ng a.(c) Okara ..(4) Qadirahad.(e) Scranwala,

(/) K .oU a. Jinda Ram .( g o ) Kat SuJan Singh.

JE I,asedon the experience of Bdtis 1 1 R a i~w ay s. a n d th e reco rnm en da tio nso f th e C ( )n sw l .i3 i.n~s ,eheieebetween A~[ or O il insulated equipm ent for thesetrackfeed .e l sta tions and . trac t sec tion ing cab ins equipm.ent has been rnadejn favourof Sw itch ,g ,ear and C ow ans ou tdoor oi.~.insulated 'equipment. Thecireaitbreakers ferthe 2 0 5 KV sys.temwould be of the single phase, oil insulatedoat-do O . I r ' parte rn bav ing , a breiling capac ity of 250 M V A and arranged for motorweuad spring dosed, compress ion springepened opera tion . These w ould be. . . . - =remote eontrelled tbrough supervisory Control System based. at Lahore and.f itte d. w i th fully inter-locked op e ra te d . I so la te e s on both incoraieg and ,ou ~.go- i:rn gsides.PN~eetiveS y s t C o l m

Track Feeder' BUl l ions . The overall :SY8tem is 0 1,d dle d into IncomingPow er S upp[y Proteotiou and Tll'a.ek:Feeder Protection.

The iBCOming feeder are suppli.ed from Grid Sub-Stations either Iromtw o 1...5 MVA Transform er to the sam e pa .ir ,o ,f supp ly phases such as at KotLakhpat and Sa.hiwal, in which easethe ]Busl'"cQ,upler iS iI1 0rmaL ly ,c1GSOO ,o ru nth e :SUl.ppl~es~npar.all.e:lnd , tnerefore,.8 balance over current s ystem is re qu ire d.o r w here the supply T ransfcm iers are ,o f 5 M V A 'capac ity ~ no 'p ,aI;raJ1 e~ .Ipt:Fado 1 i!lis req il!.liredand ,~herefo re , sim ple incom ing feeder over eurren tp ro tec t~ (lin ~s:p rovided .. A s an . instance there w e tw o supplies at W an R adha Ram tappedf rom ,d if feven t ,supip,ly phases and are not to beparalleled; a, SJst;e;m o,r EleclricaJi ,mter - Iocking ~:S fitted. , on th ls swi tc .h bOlard to p re ven t elosure of the tw o feederbreakersand the bes-coupler at the same time,0) O v e . r - c u r . r e n t . P : r o , t , e c t i o . l l

There are tw o basi.c type 0 , ' ~ )v 'e ~c u.n en t s y:s ~em s u t i H : z : ii n g FO L oyerloune!Olt instantaneous re~ay;s with the fO UO wlDiS sp ecm.c atio us. :- -


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ersRelaye o n . CurrentSetting RangeTiming Re]a.ySetti ng : Range

P A P E R N ~ " .3 , 9 25MVA

. ~ . l o o n15 MVA.3:0011

f. G.L.I A100%,-400%

AK.A2 AXBl0 . .2 - 2 S e es .

(U) Transformer Winding 'Eempe.rature lmlicatio'n .Re lay :Typ6 W. T.Tidsrel ay is eenncctedto the Supe:r\"isoryCoatrolt give au ~nw'(;ati'oill

of the winding temperature of the Transformer enloed.(iii) Re~erse .Power Prmection T y p e NBN2.

W.here two, : supp~y transformers are connected inparaUe~~power couldf i. o,w i n th e reverse direction through one of the inc om in g feed er c ircu it breakers,should the MV circuit breaker supplying that eircuit open..for any reason, Inorder to stop the tiI.owin the reverse direction, the N iBN2 relay .w sloo.nnectOO. totrip associated c.~rc-1!l~treaker i .rnstantane>ous~y. The details of setting are:

ers.v. T . su pp lyRela.ySetting Range

3000novNBN21 0 ' 6 I% ~ l "11)/'_ .!," - 0- ~~ /0.

Cfv) P h as e D ftfele .n ,tia l P I ''O 'tect,ionThe sing~ephase power supplies are obtained from dim~rent pla:~r of

phases of the Grid Supply Sys~em.and on certain points all. the Railway system~'V o lta ge s E 2 0El out of phase i.e.~44 KV can occur and if the circuit breaker~_atsuch a point were elosed, a n e ffe cth l1 e phase feu It would. be applied. tothe hlSh.v ,o lta ge p ow e r su .p ply system. To el1lsure that sucha c on ditio n. is clea:rro. quicIld,'tphase d .i :l ie nm~ ia li pro tJ e ct io li l [1e~a.ys.are appliled.~o all circuit breakers acrossw hich 44 K V is likely to appear under cperating (I 'E ' emergeDC) ' c01ndidons. Thesephase dUferentialle:lays are normaJ~.yat some (!If the track sectioningcabins.T he pro te clc im ru . is b as.ic atU . y~ h[o ug h. a f'Gl. instan taneeus ever-cureent relayand is detailed as under :-

CT's .RelayCo il 'C un,em t'S etting Range

400 /1F. o.r,IASO%-200 %


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(8) Trac'k Feeder Protee~ti0DAdequate and :reliabletrack feeder protectionjsmostvital for effie-llentmain te na nc e o f se rv ie es a s 2 Il~ :so hig hspeed. c le ara nc e o f short eireuits to minimise

arcing dam~ge to the overhead contact wire system. 'W~tb. a normsl supplysystem, Ioading points are fixedgeographica11y wheseasin the RaHway system,the loading poin~gare constantly moving, Thusthe train m oading currentsw ould. be seenby the con.vte]}tru .on8l .~protecHom equipmen t S] l e n as inverse timeever ..current type as fault currents. To overcome this dimculty definite distancetype protection schemes have been developed baeh by AEI and ASEA f()i[ 25KV sy.stemand are presemdy used. on the British Railways, For JP.W.R.athree Zone defini te d is tance scheme ,o,fprotection has been utillzed. The under-lyingp'rmcip~e of protection is based O .D measurement of fauh.jp.alili impedanceand! operation. ,of the: uJ ]a.y is dependent upon the qu:():~at~(~ni-z~ faultrump,edance~which cosrespeads to a definite length of track feeder termed asZone. The applieation of eaeh set of Distance Protectien is such that the Zon.eI is set to measure 85% of the first track section i.e.t distancebetween sub-s 'tatioM"Zo,ne . 2 : operaees fo r faults oC'Cu[r~, l lgwithin the remaining : t S % andalso ext'{}ndiol io:to :S Ol% , ,of the: second track seesion, and Zone 3 operates forfa ults o cc urr in g wi tbimlbe r e . m , a , [ m n g ; 50% and. a pp rox iJma!~e~y25 % of the thirdU:lct section.

Tille approdmate opera.'Ill~times f~)ilt' faults appearing in the various:zones are :~Zone R:e lay T imeSeconds D.C ..S. OperatioaSeoonds T otal TimeSeeonds

L2 .3 .

0.06 t()0.20.. 5 ,

1*

o . i s ,( 1 1 , . 1 50.1):

0.:21 to 0.351 0 , , 1 6 51.U

Recote Control Supervisory SystemCentral Electric Traction Remote Control C-entre has bem estabHshed

at Lahore wwth a. view to ensuring continuity of power supply as also to have aeamprehenslve picture of supply conditions, and the means te o pe ra te ,s w itc l1 l.-gear at allF,eooer Stad'OiDS, and Track Sectioning Cabins, The centrol centrewould comprise Ccntrcl Room, ApparatuS! Rocm, Battery Room and otherfacilities. The SupelviS{Hry COl!ltto:~will 'be lexeILcised. by T:ractioD Controllersthrough a common Diagram System. The s:ystem wo'llldbe capable of 'control


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PAPER No. 3929Dd~liIdic~t:io:rn.o f any one Track Feederor sectioning stationsat a . time wi thprovision for registedng on a.mimic diagram by means of set upkeys, the indiv~~dual indication for a n Track Side Stations. Each controlled circuit breakerand motorized switch is represented on. the diagrama.nd sw itches and lamps'have been prov ided for the foU ow ing ' purposes :-

({) Operatlog Circuit Breaker and Switches.(U ) Accept ing and cancelling alarm a,(iii) Checking indica don.(tv) Testing the indicaHng [amps.

( 1 1 ' ) Opera tins an d . md ic a tin g dummy c l rc uit b re ak er ,Through the Tele-communication cable systems" the control and mdiea-

tion of the position of c ircuit b reakers and sw itches is transm itted over p ilotcables from the Feeder Statioesend Track Sectioning CaMus to ' the ControlCentre,Emer:gencyPower Sl!Ip'ply Alli'ang~Du~nfs,

Under norma] feeding arrangemeets, Kat Lakhpet Track Feeder Stat~oow in feed through the Track Sectioning Cabin at Raiwind upto Chhanga M~ulga.While one 5 MVA Transformer atWan Radha Ram W . m feed from the others~de up to Chhanga Manga and the second. 5 MVA Transformer up' to Okam~Sahiwal wi l l feed through Qadirabad Track SectIoning Cabin up to Okara andon the other side up to Kotla J inda Ram through Soranwala Track SectioningCabin .. Mian Channun Track Feeder Station win feed np to Kotla Jinda Ramen one side and Kat Suja.n , S ingh on th e ether side~ while, K hanew al w iH feed.up to, Kot Suja]l Singh onthe one aide and up to the limit of energisatioatow ards M u Han end. These arrangem ents are shownin FigureS, .Em c :r ge lilCY A r ra n :g ,eme !l!lt s u n d e r Ou t a~e Condit ions,C ase I :-Comple.t,e Eaiture of Mian C ha nn un a nd ' OneS MVA T r am ! o rme r ou t

at Wan Raina Ram .:Diagram 'c' r u n Figore B, shows the feeding arrangements, shouldsituation arise resulting in complete failure of Mian Channen PowerSupply and outage of o ne T ra ns fo eme r at Wan . Radha Ram. Itmaybe seen.that Kat Lakhp.at would be able l LO ' supply lU lp~O' Wall RadhaRam through closing of both Ralw lnd and Chhanga Manga : TrackSectionsng Cabins and Sahiwal WQuId. supp~yup to to MWDChaoounthrough Soranwala and Kotla l inda. Ram Track Sect ioning Cablns,whi le Kbanewa l wouk1 l .mee t the requ irem ents up to th e other side ,ofthe neutral section of M ian Channun t'h w u g'h l K () t S llja n Singh Track.: S e c t i o m m ' g CabiD f


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- - -, - ~~ .. -_.- - -_. - - r~.n ,,_ .,_ __ ___ ,., ,. __ r .~ . . . .

s oCmse 2. : -C'ompl 'e te Failut ,e 'qf bo th : W : a n Rad ko . Ram end Al lan: Ci ummm :

This .wsa. rather severe case as with. complete outage al Wan RadhaRam and Mw an e h a l l l 1 l t 1 i J D , although EDt Lakh.pa.t and Sahiwal wouldb e - able to meet the: demand ofWa:n Radha Ram,S: sectionabout i6mi~.esbetween Kotla Jinda Ram and Mian Channun w m be outof operation, Arran~emen~sproposed are shown in Diagram '.D~of Figure 8. Traffic c()uldihowevell '~ beregula ted to, cvercome tbis,

The main back stay of the power sl],pply requiremen ts for .Ra i lwmyoperation are Kat Lakhpat and S~hiwal Track Feeder Stations and , in case ,of a .C iom p.~.eteoutag e (In any one ,of the&e.,ttain opera.6on w ould be seriously dis-turbed. It is, however, andc~pated that situation of thls kind would not ariseas WAPDA has su.mcieI1ltlyre~in~()rced their U2KV net-workat these twoplaces.OtberF,eatme:s.

There is aften mention ofuabalanee loading and harmonies caused totbe 8u~ply system thmugh the use or single phase tractlea reqnlrements, eon-s~derab1e research has been carried ,out on the Sillbject aad generally it is ,concl uded that impact of slnglephase traetion requirements ofa system subjectto certaineondltlcns is invariably williin.permissible limits and no undue adverseeffect is manifested. on, the supp'~y systemasa result thereof. Brie.fty unbalancedloading can. cause :(0Unbalancedvolteges and currents,

(Ii) Reduction i:o.capaci~.y o , r 3 phase net works ..(iii) Over heating generators.

A c-heck and contrel ofthese eonditions isensured 'b y various means,In. the :filrstinstance where sing[epbase demand as a functicn ' O l f . 3 pbaseshortcircuit capacity of the supply system at that poin t is witl:dn 5 '% as, is mostlythe case for Labo,lie"KhanewaJi Electrificaticn except at Wan Radha Ram, theunbalance expected is within safe limits. In ceucluslon, the higber the p~imarysupply voltage~,tb.e lesser the unbalance. To, obviate a.n:Ylestdct~om in. thecapa.c~tyof 3 phase network, arrangemea ts have beeamade to connect supply todifferent pair of phase'S: Tothatend at Kot Lakhpat, the two transfcemers areconnected to Yellow and B ~.uepha se s of th !e il l 32 K V sy stem , ,atW.a:n Radha Ramto Red, and. Y eU ow pm ases of the 66, K V system~ all Sahiwal to Red and Yellowphases of lil2 K,V system, at Mian. Channun to ,eUow and ,Blue phases of 66K .V ' 8 u s b a \ 1 L w hile a t Khanew al to B ~ueandl Red phases of > 66,XV W APDAin feed. Lastly as the sin~e phase d~mand would be tapped from th e integrated


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. '. - . . - ~ . . . . . . . , . ~ . -

___I

'.


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53Grid s:yst,emand would be speeadon the various generators, it~s expected. thatTurbo Generators p3l'dcl!Ilady ,atM ulta n w

Railway Electrification Power Supply

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