74155338 Electric Traction

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5/3/12

Power System-IIIByJ.SOMLAL, M.Tech.,(Ph.D), MISTE, MIETE,

Assistant Professor,EEE Department, L !ni"ersity,#a$$esh%aram, #i&aya%a$a,An$hra Pra$esh'*+e- http-%%%./01ni"ersity.in

Moi0e 2o-334356787



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ELECTRIC TRACTION

v What is Traction?

Ø The act of $ra%in9 or p100in9, as y an e0astic orsprin9 force.

Ø Traction refers to the ma:im1m frictiona0 forcethat can e pro$1ce$ et%een s1rfaces %itho1ts0ippin9.

Ø TRACTION is res10tin9 from a specificFRICTION coefficient (i.e. friction et%eenr1er an$ 9ro1n$) comine$ %ith area of

9ro1n$ co"ere$ y the tire – FOOTPRINT



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Why "o we nee" traction?

v +e00, that ;1estion comes 1p e"ery once in a

%hi0e. Its a 9oo$ ;1estion<Ø If o1r feet $o not fin$ a s1rface %ith 9oo$ 9rip

(traction) o1r 0e9s an$ feet co10$ not mo"e 1s

for%ar$.Ø Same story for a car ' if the 9ro1n$ %o10$ not

pro"i$e eno19h resistance (traction) the force

9enerate$ in the en9ine %o10$ not e a0e tomo"e the car for%ar$.

Ø The scenario is ;1ite simp0e. The more traction

can e ma$e a"ai0a0e the more tor;1e can eenerate$ to mo"e more %ei ht.



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Re#$irements of an I%EAL Traction System

The fo00o%in9 are some of the important

re;1irements of the $ri"in9 e;1ipment 1se$ fortraction p1rposes-

Ø The coefficient of a$hesion(stic/in9) sho10$ e

hi9h so that hi9h tracti"e effort at start is possi0ean$ rapi$ acce0eration of the train can eotaine$.

Ø It sho10$ e possi0e to o"er0oa$ the e;1ipmentfor short perio$s.

Ø The %ear(cons1me y 1se) ca1se$ on the shoes,%hee0 tires an$ the trac/ sho10$ e minim1m.

Ø It sho10$ e ossi0e to 1se re enerati"e ra/in



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Traction Systemv =. 2on'E0ectric Traction System- Does not 1se

e0ectricity at any sta9e. E:- Steam En9ine Dri"e,Interna0 >om1stion Dri"e.

v . E0ectric Traction System- If e0ectric s1pp0y is

1se$ for $ri"in9 a 0ocomoti"e, the system is/no%n as e0ectric traction.

Ø In"o0"es 1se of e0ectricity at some sta9e or other.E:- Battery E0ectric Dri"e, Diese0 E0ectric Dri"e,etc.

Ø E0ectric traction is the most efficient of a00 othersystems an$ is 9oin9 to e the f1t1re system to e

a$opte$ y a0most a00 co1ntries of the %or0$.



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Ty&es of E'ectric Tractionv #ehic0es %hich recei"e e0ectric po%er from a

$istri1tion net%or/ fe$ at s1ita0e points fromeither a centra0 po%er station or s1stationss1ita0y space$.

It is f1rther s1$i"i$e$ into

Ø =) Systems operatin9 %ith $.c. s1ch as tro00ey 1ses, tram%ays an$ rai0%ays.

Ø

) Systems operatin9 %ith a.c. s1ch as rai0%ays.v The 9ro1p consists of se0f containe$ 0ocomoti"es

i.e. they 9enerate their o%n po%er.

It is f1rther s1$i"i$e$ into



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v The $iese0 e0ectric 0ocomoti"e 1ses a $iese0en9ine to $ri"e an e0ectric 9enerator, %hich thens1pp0ies the c1rrent to traction motors, %hich are9eare$ $irect0y to the 0ocomoti"e?s %hee0s.

Ø In In$ia, the $iese0 0ocomoti"es %ere intro$1ce$in =36 for sh1ntin9 p1rposes on roa$ 9a19esection an$ in =38 for main 0ine ser"ices on

me$i1m 9a19e section. The $iese0 e0ectric0ocomoti"es emp0oye$ in practice are of thefo00o%in9 types-

Ø

=. Main 0ine $iese0 e0ectric 0ocomoti"e ha"in9en ines of o1t 1t not e:cee$in =** /+ an$

%IESEL ELECTRIC TRACTION



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• AD#A2TA@ES

Ø The initia0 in"estment

re;1ire$ is 0o% ascompare$ to $irecte0ectric traction sincethere is no nee$ ofo"erhea$ str1ct1re$istri1tion system an$e;1ipments.

Ø D1e to its hi9heracce0eration an$retar$ation, the

sche$10e spee$ o"er ai"en ro1te %i00 e

• DISAD#A2TA@ES

Ø Its o"er0oa$ capacity

is 0imite$.Ø The 0ife of the $iese0

en9ine is

comparati"e0y shorter.Ø In a$$ition to motor

9enerator set, specia0

coo0in9 system isre;1ire$ for coo0in9the $iese0 en9ine a0so.

Ø Its r1nnin9 an$maintenance costs are



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Ø It is the most %i$e0y 1se$ traction system in %hich the "ehic0e $ra%s

e0ectrica0 ener9y from a $istri1tion system fe$ at s1ita0e points from acentra0 po%er station or s1station.

Ø In In$ia oth A> an$ D> type of e0ectrifie$ train systems operate to$ay.

Ø =** # D> ase$ train system is most0y operatin9 in M1mai area. It is

ein9 con"erte$ to /# A> system. Cest of the In$ia %here ro1tes aree0ectrifie$ most0y operates 1n$er /# A> o"erhea$ %ire.

Ø The e0ectric 0ocomoti"es are of t%o types

ü A.>. 0ocomoti"e

ü D.>. 0ocomoti"e

Ø In case of $.c. 0ocomoti"e $.c. motors are 1se$ for traction. The fi9.=sho%s a schematic 0oc/ $ia9ram of $.c. 0ocomoti"e.

Ø It asica00y consists of a step $o%n transformer, a f100 %a"e rectifier %ithfi0ters an$ $.c.motors. The fi9. sho%s an a.c. type e0ectric 0ocomoti"e.

ELECTRIC LOCO(OTI)E



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• AD#A2TA@ESØ Since e0ectric motors are 1se$ as the $ri"es , the

system is c0ean an$ po001tion free. Startin9 tor;1e

is hi9h, so hi9h acce0eration is possi0e. Spee$contro0 is "ery simp0e. Bra/in9 is simp0e an$efficient. E0ectric ra/in9 is 1se$ in this case%hich is s1perior to mechanica0 ra/in9 1se$ ysteam an$ $iese0 0ocomoti"es. It is possi0e toapp0y re9enerati"e ra/in9 %hich has thefo00o%in9 a$"anta9es

ü Ao"e 4* of ener9y spent $1rin9ascent(1p%ar$ mo"ement) is p1mpe$ ac/ $1rin9$escent.

ü Less maintenance of ra/e shoes, %hee0s, tyres



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%ISA%)ANTAES

Ø The most important factor a9ainst e0ectric

traction is hi9h capita0 o1t0ay on o"erhea$s1pp0y system. Therefore, 1n0ess hea"y trafficis to e han$0e$ e0ectric traction ecomes1neconomica0.

Ø Po%er fai01re for fe% min1tes can ca1se$isr1ption of traffic for ho1rs.

Ø

The e0ectric traction system is tie$ to e0ectricro1tes on0y. ence it cannot e 1se$ on any ofthe ro1tes.

Ø In case of A.>. traction the comm1nication0ines r1nnin9 a0on9 the trac/ e:perience

Wh t th 't " f ' t i t ti i



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What are the *o'ta+es $se" for e'ectric traction inIn"ia?

Ø #o0ta9es 1se$ are =./# D> an$ /# A> formain0ine trains.

Ø >a0c1tta ha$ an o"erhea$ 7/# D> system 1nti0 the?8*s.

Ø

The =./# D> o"erhea$ system (ne9ati"e earth, positi"e catenary) is 1se$ aro1n$ Bomay (Thisinc01$es M1mai >ST ' a0yan, a0yan ' P1ne,a0yan ' I9atp1ri, M1mai >ST ' Be0ap1r '

Pan"e0, an$ >h1rch9ate ' #irar).Ø >on"ersion to /# A> has a0rea$y een $one on

the Tit%a0a'asara section ne:t to e con"erte$

are hapo0i'#an9ani, #an9ani'Thane, an$



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System of Trac, E'ectrification

Present0y, fo00o%in9 fo1r types of trac/ e0ectrification

systems are a"ai0a0e-v %irect C$rrent System D> at 8**'5* # is

1ni"ersa00y emp0oye$ for tram%ays in 1ran areasan$ for many s11ran rai0%ays %hi0e =**'7***# $c is 1se$ for main 0ine rai0%ays. Lo% "o0ta9e $csystem is 1n$o1te$0y s1perior to sin90e phase acsystem for hea"y s11ran ser"ices.

v ./0 Sin+'e Phase AC System In this system acseries motors are 1se$ for 9ettin9 the necessarymoti"e po%er. The "o0ta9e emp0oye$ for

$istri1tion net%or/ is = to " at =87 or



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Ø 53 Sin+'e Phase To %irect C$rrent System

This system comines the a$"anta9es of h" ac$istri1tion system an$ $c series motors fortraction. The "o0ta9e 1se$ for o"erhea$$istri1tion system is /" at norma0 s1pp0y

fre;1ency of * F. The 0ocomoti"e carriestransformer an$ con"ertin9 machinery to step'$o%n the "o0ta9e an$ con"ert into $c. Thissystem of trac/ e0ectrification 1sin9 /", *F, sin90e phase ac s1pp0y has een a$opte$for a00 f1t1re trac/ e0ectrification in In$ia. Thea$"anta9es of s1ch a system are 0i9ht o"erhea$

catenaries o%in9 to 0o%er c1rrents, 0ess



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Ty&ica' Rai'way Ser*ices

S.2o Parameter of>omparison

!ran or >ity Ser"ice S1'!ran Ser"ice Main Line Ser"ice

= Acce0eration =.'6mphps =.'6mphps 8'4mphps

Cetar$ation 7'6mphps 7'6mphps =.mphps

7 Ma:. Spee$ =*mph =*mph =8*mph

6 Distance et%eenstations

=m ='4m G=*m

Specia0 remar/s ifany

ree r1nnin9 perio$ is asentan$ coastin9 perio$ is sma00.

ree r1nnin9 perio$ is asentan$ coastin9 perio$is 0on9.

Lon9 free r1nnin9an$ coastin9 perio$

s. Acce0eration an$ ra/in9 perio$s aresma00comparati"e0y.



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TRAIN (O)E(ENT-SPEED TIME >!C#ES

Ø A train is to e r1n most optima00y as for as

possi0e.Ø for this it is necessary to /no% the spee$ time

c1r"es so that it is possi0e to fin$ o1t %hat

ener9y m1st e s1pp0ie$ to the train to perform a partic10ar &o.

Ø The s0ope at any point of the c1r"e 9i"es the

acce0eration or retar$ation of the train at thatinstant of time.

Ø The area et%een the c1r"e an$ the time a:is 1p

to a certain time 9i"es the $istance co"ere$ y thetrain ti00 that instant of time.



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Ø (iii) ree r1nnin9(t't7)-This perio$ occ1rs %henthe po%er o1tp1t from the $ri"in9 a:e0s a0ancesthe rate at %hich ener9y is e:pen$e$ a9ainst theresistance to motion.

Ø (i") >oastin9 perio$(t7't6)- At the en$ of freer1nnin9 perio$ , s1pp0y to the motors is c1t off an$

train is a00o%e$ to r1n 1n$er its o%n moment1m.

Ø (") Bra/in9 perio$(t6't)-At the en$ of coastin9 perio$, ra/es are app0ie$ to rin9 the train to

stop.

Crest S&ee" A*era+e S&ee" An" Sche"$'e



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Crest S&ee"6 A*era+e S&ee" An" Sche"$'eS&ee"

Ø >rest spee$ is the ma:im1m spee$ (#m) attaine$

y a train $1rin9 the r1n.Ø A"era9e spee$ is the mean spee$ from start to stop

i.e. the $istance co"ere$ et%een t%o stops

$i"i$e$ y the act1a0 time of r1n is ca00e$ thea"era9e spee$.

Ø Sche$10e spee$ is the ratio of $istance co"ere$ et%een t%o stops an$ tota0 time of r1n inc01$in9the time of stop.

Ø The sche$10e spee$ of a 9i"en train %hen r1nnin9on a 9i"en ser"ice (i.e. %ith a 9i"en $istance

et%een stations) is affecte$ y (i) acce0eration



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%irect C$rrent (otor Contro'



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CONTROLLIN

v %C (otors

Ø or a D> motor, Tor;1e

TH*.=3K Ia AP 2'm HIa

Ø For sh$nt motor is constant for a constants1pp0y "o0ta9e, so, the tor;1e is $irect0y proportiona0 to the c1rrent $ra%n y the motor.

Ø For series motor Ia, therefore T I.

Ø EH#'Ia rH K2P8*A

Ø 2H(8*AKP)(#'Ia r)



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• THE SIEMENS EECT!IC !"I#"$ laiddo%& at t'e (erli& E)'ibitio& o* 1+,-.

T'e s'ort li&e %as about 00 yards

lo& a&d curre&t %as dra%& *ro at'ird rail bet%ee& t'e track %'ic'acted as t'e retur& to t'e dy&ao.

T'e locootive 'auled a a)iuo* soe t'irty 4asse&ers at a s4eedo* about *our iles a& 'our. T'is'istoric illustratio& s'o%s o&e o* t'eearliest trai&loads o* 4asse&ers

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74155338 Electric Traction

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