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    Transmission Line Applications of Directional Ground Overcurrent Relays

    Working Group D24 Report to the Line Protection Subcommittee

    Draft FSeptember, 2010

    Working Group Member! Don Lukach "#hairman$, Rick %a&'or "(ice)#hairman$, *effre&

    +arch, en +ehren-t, Martin +et, Mike +'o-er, Ran-& #re''in, Ran-& #unico, .''a

    Deron/a, ormann Ficher, Dom Fontana, Rafae' Garcia, Gene enneberg, Me&er ao,Wa'ter Mc#annon, +ruce Mackie, *ohn Mi''er, Dean Mi''er, *im 3+rien, #ritian Pa-uraru,

    Manih Pate', .'e/an-ro Schnakofk&, Don Secik, Stee %urner, ar' 5immerman,

    1 Introduction 6Manih Pate'7

    %hi report i prepare- for the Line Protection Subcommittee of Po8er S&tem Re'a&ing

    #ommittee on the app'ication of -irectiona' groun- oercurrent re'a& for tranmiion 'ine9Groun- -itance an- groun- oercurrent re'a& are mot common re'a& ue- to protect

    tranmiion 'ine againt groun- fau't9 o8eer, 8hen fau't impe-ance i ignificantgroun- -itance re'a& are 'e enitie than groun- oercurrent re'a& an- often 8i'' not

    repon- proper'&9 Groun- oercurrent re'a& can be et enitie enough to -etect high

    impe-ance fau't on tranmiion 'ine9

    %hi report -icue fo''o8ing criteria to coni-er 8hen app'&ing groun- oercurrent re'a&

    for protection of tranmiion 'ine againt high impe-ance fau't9

    Determination of re'a& etting an- coor-ination to enure re'iabi'it& an- e'ectiit&

    of protection &tem9 :ffect of geo'og& on groun- fau't current an- hence re'a& etting9

    :ffect of ing'e po'e tripping9

    :ffect of &tem reconfiguration uch a rec'oing an- maintenance outage9

    #oni-eration of 'ength of the protecte- 'ine9

    ;mpact of contingencie a it can ignificant'& change f'o8 of fau't current on the


    #oni-eration of mutua' coup'ing a it can hae ignificant impact on groun- fau't


    ;mpact of ariou groun- ource inc'u-ing their accurac& in &tem mo-e'

    +enefit of uing a-aptie capabi'it& of microproceor bae- re'a& to enhancere'iabi'it& of protection &tem -uring &tem change9

    +enefit an- iue of uing negatie e

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    2 Purpose

    %hi report -icue the /utification an- app'ication criteria for -irectiona' # re'a& for

    groun- fau't -etection a app'ie- for protection of tranmiion 'ine9 %hi report -oe not

    coer po'ari=ation topic, pi'ot cheme etting practice, or reonance groun-ing9

    3 Definitions

    %hi report ue termino'og& that i conitent 8ith other ;::: tan-ar- an- gui-e9 o

    ne8 term or -efinition are intro-uce-9

    4 ummary

    Senitie groun- fau't protection i uti'i=e- to remoe ha=ar- from the pub'ic an- protecte

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    . an a'ternatie, negatie e91 #omparion of groun- oercurrent re'a&ing 9 groun- impe-ance -itance re'a&ing

    >9191 %ra-itiona' #omparion

    Groun- oercurrent an- groun- tep -itance are the mot common groun- fau't -etection

    metho- in tranmiion 'ine protection9

    %he groun- oercurrent protectie e'ement repon- to =ero)e

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    e'ement i not affecte- b& phae)to)phae connecte- 'oa-,uch a -e'ta)8&e tranformer9

    %he e'ement i a'o not affecte- b& 'o of o'tage con-ition9

    #onere'&, protection uing groun- oercurrent e'ement ha eera' 'imitation9

    Groun- oercurrent e'ement are affecte- b& change in the po8er &tem ource, thu are

    more uceptib'e to 8i-e ariance in operation for &tem con-ition9 +ecaue thetranmiion &tem configuration change, the pickup etting ma& nee- to be reie8e-

    more fre

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    ;mpe-ance 'imite- groun- fau't are more 'ike'& to occur in area 8ith poor oi' reitiit&9

    Region 8ith an-& oi' or 8ith igneou rock formation great'& increae the probabi'it& that

    groun- fau't 8i'' be re-uce- in magnitu-e becaue of higher impe-ance in the groun- returnpath9 Rock& an- an-& oi' con-ition a'o make it -ifficu't to proi-e 'o8 to8er footing

    reitance9 igh to8er footing reitance contribute to higher groun- return path impe-ance

    for fau't, uch a inu'ator f'ahoer, on tranmiion to8er9 igh to8er footing reitancea'o increae to8er groun- potentia' rie caue- b& -irect or in-uce- 'ightning urge,

    'ea-ing to a higher probabi'it& of inu'ator f'ahoer caue- groun- fau't9

    Region 8ith oi' 8here moiture i more rea-i'& retaine- ten- to hae 'o8er oi' reitiit&

    an- make it eaier to achiee 'o8er to8er footing reitance9 Like8ie, more popu'ate- area

    8ith e?tenie -itribution &tem groun-e- neutra' net8ork, un-ergroun- 8ater piping

    &tem, etc9, he'p to re-uce the fau't current return impe-ance path9 Ditance re'a& arebetter uite-, an- more 'ike'& to -etect a higher percentage of groun- fau't in thee region

    becaue of a 'o8er probabi'it& of encountering a fau't 8ith ignificant groun- path


    >92 Determination of Pickup Setting

    %he ro'e of -irectiona' groun- oercurrent re'a&, 8hen app'ie- to 'ine haing groun-

    -itance protection, i to upp'ement the -itance e'ement an- the high et intantaneouoercurrent unit for fau't 8ith current 'ee' 'imite- b& reitance9 . uch, the pickup of

    thi protection i not t&pica''& bae- on &tem coni-eration, uch a 'ine impe-ance or

    'ine)en- fau't current 'ee'9 %he inc'uion of =ero ek( fau't

    uing 200 ohm, a'ue are t&pica''& aroun- 00 amp9

    .nother metho- of -etermining the pickup i to moe the >1 coor-ination point to that of

    the >0 reach of the ne?t bu, thu enuring an acceptab'e coor-ination intera'9

    When pickup a'ue of thi 'ee' are app'ie-, it i poib'e an- -eirab'e to -e'a& tripping for

    fu'' magnitu-e 'ine)en- phae)to)groun- fau't to time that coor-inate 8ith the groun-

    -itance =one 2 re'a& trip time9

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    . a etting check, fau't imu'ation hou'- inc'u-e a 'ine en- fau't 8ith en- c'oe- to

    aure that the %# e'ement etting i enitie enough to -etect thi fau't9 Refer to Figure>92919 %he fau't imu'ation hou'- take into coni-eration a'' contingent an- p'auib'e

    configuration 8ith margin9 %he ;# e'ement mut not trip for thi 'ine en- fau't 8ith the

    remote en- c'oe-, but 8i'' mot probab'& -etect thi fau't once the remote en- open, ucha 8ou'- occur -uring a e

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    For a c'oe)in groun- fau't at F1, re'a&ing at breaker + hou'- operate intantaneou'&9 ;f the

    protection fai'ure cheme i 'oca', the groun- %# time -ia' for breaker . hou'- be et toa''o8 Subtation R protection fai'ure cheme to operate firt9

    Figure >991, Groun- Fau't near the Remote %ermina'

    %he proce for erif&ing coor-ination bet8een the 'oca' %# re'a& an- the %# re'a&

    protecting a 'ine from the remote bu hou'- take into coni-eration the intantaneou trip

    app'ie- for protection of the remote 'ine9 ;f the coor-ination i erifie- uing the pickupcurrent of the remote 'ine ;# re'a&, the re-uction in fau't current reu't in better margin

    bet8een the 'oca' an- the remote %# re'a& an-, if the remote bu ha a--itiona' infee-

    ource, further margin improement 8i'' reu't9 %hi ame a-antage can be gaine- if a

    groun- -itance e'ement i app'ie- to the remote 'ine termina'9 %he coor-ination can beerifie- uing a fau't 'ocate- at the ma?imum reach of the remote termina' =one 1 groun-

    -itance e'ement9

    ;n Figure >991, coni-er a the groun- fau't F1 'i-e -o8n the 'ine9 ;n mot cae, the fau't

    current contribution from breaker . -ecreae e?ponentia''& a compare- to the fau't current

    at breaker + -ue to the effect of infee- at Subtation R9 .'o the operating time increaee?ponentia''& if a @moreA inere characteritic cure i ue- an- the fau't current 'ee' i in

    the 'o8er mu'tip'e of pickup part of that cure9 ;f the remote ubtation i a 'ine in, 'ine out

    ubtation, cure e'ection i critica' a'ong 8ith time -ia' etting9 %hi can be i''utrate- inFigure >99 an- Figure >9949

    Figure >99, Line in, Line out

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    1 10 100


    Multiples of Pickup

    Chart Title

    Curve A

    Curve B

    Figure >994, %# #ure

    For fau't at F1 in Figure >99, the criterion in etting the time -ia' of the groun- %# re'a&

    + at ubtation R i the ame a -ecribe- aboe9 ;f there i not a groun- ource at

    Subtation R, the time -ia' for re'a& . at Subtation L mut be et to coor-inate 8ith re'a& +at Subtation R for fau't at F19 . i''utrate- in Figure >99 an- Figure >994, for a o'i-

    groun- fau't at F1, the fau't current i 10 mu'tip'e of the pickup for both re'a& . an- +9 %he

    trip time for Re'a& + an- Re'a& . are 0 c&c'e an- 4> c&c'e, repectie'&9 o8eer, poore'ection of the cure t&pe for re'a& . an- re'a& + can 'ea- to micoor-ination a ho8n in

    Figure >9949 ;f the fau't at F1 i of reitie t&pe an- the fau't current i 'e than > time

    mu'tip'e of the re'a& pickup, one can c'ear'& ee the micoor-iantion for both re'a&9%herefore the re'a& . cure t&pe mut be of imi'ar or @moreA inere characteritic than that

    of re'a& +9

    %he ue of groun- time oercurrent e'ement in con/unction 8ith groun- -itance e'ement

    often proi-e the a--e- benefit of better enitiit& for groun- fau't in the 'at 10H to 20H

    of the 'ine9 5one 2 impe-ance e'ement t&pica''& ue -efinite time -e'a& regar-'e of fau't'ocation9 For fau't in the 'at part of the 'ine, the remote en- t&pica''& trip intantaneou'&9

    %hi remoe the remote infee- an- a''o8 the groun- intantaneou e'ement to poib'&

    reach farther an- pee- up tripping9

    Specia' coni-eration hou'- be taken into account 8hen coor-inating -irectiona' groun-

    %# re'a& or e'ement, epecia''& if pi'ot cheme are not emp'o&e-9 %he ob/ect of the

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    coor-ination hou'- be to obtain the combination of the fatet operation of the 'oca' re'a&

    being et "b& inc'u-ing a'' groun- ource$, an- the 'o8et operation of the remote re'a& "b&

    remoing a 'arge groun- ource uch a a 'ine or autotranformer$9 Where 'ine are proi-e-8ith high pee- pi'ot protection, an outage of thee cheme can be coni-ere- a contingenc&

    in 'ieu of groun- ource remoa'9

    >94 Sing'e Phae %ripping

    . ing'e phae trip an- rec'oe &tem i one 8hich trip on'& the fau'te- phae on a ing'ephae to groun- fau't an- trip a'' three phae of the circuit breaker on a mu'ti)phae fau't9

    For a ing'e)phae trip the &tem 8i'' automatica''& rec'oe the open phae after a uitab'e

    time intera'9 ;f the ing'e)phae fau't ha c'eare-, the &tem reet9 ;f the ing'e)phae

    fau't i ti'' preent, the &tem trip a'' three phae of the breaker, an- make no furtherrec'oing attempt9 For a mu'ti)phae fau't, the &tem ma& or ma& not automatica''&

    rec'oe, -epen-ing on the cheme programming an- the operating re

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    >9> :ffect of S&tem Reconfiguration

    %he tranmiion &tem i not a'8a& in the ame configuration -ue to eera' factor, ucha rec'oing an- maintenance outage9 %he change to the &tem can impact groun- ource

    an- thu affect oercurrent groun- re'a& operation9

    >9>91 :ffect of Rec'oing

    Rec'oing i a pecia' cae of a &tem configuration change, a it repreent a non)t&pica'operating cenario 8here one termina' of the 'ine i c'oe- 8hi'e the other en- i open a

    ho8n in Figure >9>919 n 'ine 8here pi'ot protection i not ue- or not aai'ab'e,

    intantaneou -irectiona' groun- protection can coer a ignificant percentage of the 'ine9

    %he etting of the ;# re'a& or e'ement i t&pica''& bae- on the current that f'o8 for aremote termina' groun- fau't, 8ith a afet& margin "a mu'tip'ier of 192 or 19 i t&pica'$

    app'ie- to aoi- oertripping9 . rec'oe of a remote 'ine onto a c'oe)in fau't "8ith en- open

    or c'oe-$ i oftentime the e?terna' fau't imu'ation ue- to et the 'oca' termina' re'a&, a it

    ten- to force more groun- current through the termina' being et9 Remoa' of remotegroun- ource prior to fau't imu'ation hou'- be coni-ere- for t&pica' maintenance

    outage an- e?pecte- &tem reconfiguration -ue to fau't c'earing9

    Figure >9>91 Rec'oing 1

    >9>92 Maintenance utage

    Remoa' of 'arge remote groun- ource -uring maintenance outage can hae the ameeffect a that of rec'oing9 %he reu't i that more groun- current 8i'' f'o8 from the 'oca'

    termina' thu impacting oercurrent etting9 During norma' operation, 8ith a'' groun-

    ource in erice, the reach of the -irectiona' groun- re'a& 8i'' be horter, but i preferre-to oertripping 8hen the ource i remoe-9

    >9 Line Length #oni-eration

    %he 'ength of a tranmiion 'ine p'a& an important ro'e in -etermining pickup 'ee' an-

    enitiit& re

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    a$ Short Line, S;R K 4

    b$ Me-ium 'ine, 09> S;R 4

    c$ Long 'ine, S;R 09>

    For hort 'ine, there i 'itt'e -ifference bet8een the c'oe)in fau't an- 'ine)en- fau't 'ee'9

    :en a 'ine coni-ere- ph&ica''& 'ong cou'- be c'aifie- a a hort 'ine if it ha a rea'tie'&high ource impe-ance that reu't in a 'arge S;R9 ;ntantaneou oercurrent e'ement that

    trip -irect'& hou'- not be ue- on hort 'ine becaue the -ifference in fau't current i

    inufficient to -icriminate bet8een near)en- an- far)en- fau't9 ;ntantaneou -irectiona'groun- oercurrent re'a&ing i, therefore, not a goo- choice for protection of hort 'ine

    un'e app'ie- in a pi'ot cheme9 Since the -ifference in fau't current i ma'' bet8een the

    t8o en- of a hort 'ine, the e'ection of time)oercurrent "%#$ pickup, an- time)-ia' 8i''be -epen-ent on coor-inating 8ith the uptream an- -o8ntream re'a&ing9 ;f margin are

    inufficient for a-e k( tranmiion 'ine 8ith S;R a'ue in the range of 19> 2909 +othre'a& hae a 0 . pickup an- there i a coor-ination margin of 090 econ- for a 'ine)en-

    groun- fau't9 ote that the time)current characteritic proi-e an inere characteritic up to

    their repectie intantaneou pickup9

    Figure >992 -ip'a& time)current characteritic for the ame re'a&, but the pickup hae

    been re-uce- to 120 .9 %he repectie timing that each re'a& operate for the 'ine)en- fau'tcon-ition ha been maintaine-, but the coor-ination margin i re-uce- to 091> econ- for the'ine)en- groun- fau't con-ition9 With the enite pickup, the %# portion of the cure i

    near'& f'at up to the intantaneou pickup an-, therefore, -oe not a''o8 ufficient


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    Figure >991, Stan-ar- %# Pickup on Me-ium Length Line

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    Figure >992, Senitie %# Pickup on Me-ium Length Line

    Long 'ine are t&pica''& eaier to coor-inate -ue to the 'arge -ifference bet8een the near)en-an- far)en- fau't current9 .n intantaneou e'ement can t&pica''& be et to coer a 'arge

    portion of the 'ine, but enitie pickup 'ee' for the time)oercurrent e'ement ma& re-uce

    performance an- ecurit&9 . an e?amp'e, a 20 k( 'ine, mi'e in 'ength can hae anaai'ab'e ing'e)'ine)groun- fau't current of 20,000 . for the near)en- con-ition but on'& 00

    . for the far)en- con-ition9 .n e'ectromechanica' re'a& 8ith E1 enitiit& for the far)en-

    con-ition 8ou'- hae a pickup of 'e than 120 .9 With a #% ratio of I00E>, a re'atie'& 'o8

    tap i re

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    percentage of =ero e991 %ranmiion P'anning Stan-ar-

    %he -etermination of 8hat the 8ore cae con-ition ma& be i a -ifficu't tak9 .n e?ce''ent

    ource for -etermining 8hat contingenc& ana'&i to ue i the in-ii-ua' uti'it&N p'anning

    tan-ar- or the :R# re'iabi'it& tan-ar-9 Some uti'itie ue p'anning criteria of )1 for

    peak 'oa-ing con-ition an- )2 on off)peak con-ition9 )1 i ca''e- @one contingenc&A,

    Page 14 of 2>

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    an- i a norma' &tem 8ith one component out of erice, 8herea )2 i a norma' &tem

    8ith t8o component out of erice9 Due to the ortheat +'ackout of 200, :R# re of 2>


    +u +

    +u D

    +u .


    +u #





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    Figure >9I91 Mutua' #oup'ing bet8een t8o circuit configuration

    Figure >9I91 c'ear'& -epict that the coup'ing bet8een circuit i not neceari'& for the 'ength

    of either one of the circuit an- -oe not hae to tart at the termina' of one circuit9 When

    uch coup'ing e?it, the =ero e9I929

    Figure >9I92 Mutua' coup'ing repreentation bet8een t8o circuit9

    Figure >9I9 :

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    Figure >9I9 i imp'& a -ifferent 8a& of -epicting the ame circuit9 For thi e?amp'e, 8hen

    the mutua' coup'ing bet8een thee t8o circuit i trong groun- fau't on one circuit can

    hae ignificant impact on the oercurrent protection on the other circuit9 %he fau't currenta een b& the re'a& at a bu 8i'' increae a the fau't i 'i- -o8n the coup'e- 'ine -ue to the

    mutua' coup'ing affect9

    Referring to Figure >9I94, the intent i to et the intantaneou groun- oercurrent re'a& at

    +u .9 Line +# i para''e' to Line .# an- mutua''& coup'e- for ome of it 'ength9 Fau't

    are be p'ace- on Line +# an- @'i-A -o8n the 'ine from one en- to the other en-9 Differentmetho- can be ue- to et the intantaneou e'ement at +u ., uch a taking the afet&

    margin time the remote bu fau't "8ith or 8ithout infee- ource out$ or taking the afet&

    margin time S%F a'ue "8ith or 8ithout infee- ouce out$9

    Fig9 >9I94 Mutua' #oup'ing :?amp'e

    %he proper etting i to fin- the ma?imum fau't 'ee', uch a 8ith tronget ource out oferice at the remote bu, an- to ue the ma?imum mutua''& coup'e- fau't9 ote, ho8eer,

    that 8ith increae- margin, the intantaneou e'ement reach ma& be ignificant'& re-uce-9

    ;f the mutua' coup'ing affect i not un-ertoo-, the intantaneou e'ement can eitheroerreach or be et too enitie9 +oth con-ition can reu't in un-eire- operation9

    %ab'e >9I91 proi-e the input for an e?amp'e of a mioperation -ue to mutua' coup'ing nottaking into coni-eration9 %he fau't current are at the 'oca' termina'9

    #'oe)in Remote +u Line :n- e?t +u Remote %ermina'

    14,0J. I . 4,>1J. II4. 1,I.

    %ab'e >9I91 Fau't #urrent

    %he etting criteria ue- for the intantaneou unit 8a to et the re'a& about 19> time theremote bu fau't current, 19>IQ11>2.9 %he other criterion 8a to et the re'a& no higher

    than 09 time the 'ine en- fau't current, or 094>1JQ02I.9 %o enure the re'a& -i- not

    operate for e?terna' fau't, the remote bu an- 'ine en- fau't out of remote termina' 8erea'o reie8e-9 Cing the ame margin, an appropriate etting 8ou'- be aboe 2>0.

    "19>1I$ but be'o8 02I amp9 . etting of 200. 8a choen an- 8a 8ithin thee

    margin9 . 'ine fau't occurre- on an a-/acent 'ine an- the an- non)fau'te- 'ine trippe- ongroun- oercurrent9 a- the engineer performe- a 'i-ing fau't in the imu'ation program, he

    Page 1 of 2>

    +u +

    +u #

    +u .Fau't

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    8ou'- hae obere- that a fau't at appro?imate'& > percent of the 'ine pro-uce- a fau't

    current of 2I00., or enough to operate the groun- intantaneou oercurrent re'a&9

    >9J .-aptie #apabi'it&

    .-aptie capabi'itie of microproceor bae- re'a& are a too' that can be ue- to optimi=e-irectiona' oercurrent etting9 Re'a& e'ement etting or 'ogic can be automatica''& a'tere-

    in repone to change in the po8er &tem9 perationa' 8itching of circuit breaker,

    b&pa 8itche, or motor operate- -iconnect "MD$ 8itche can change the po8er&tem uch that a'ternate etting 8ou'- be uefu'9 .'ternate etting cou'- a'o be

    beneficia' 8hen the groun- ource trength in the area i affecte- b& either a generator or

    tranformer outage9

    +ecaue an& of thee change affect the fau't current that can be een b& the re'a&, changing

    the etting can enhance the re'iabi'it& of the protection &tem9 . a reu't, optima' etting

    are proi-e- to the re'a& bae- upon actua' &tem operating con-ition rather than 8ort

    cae con-ition9 . coup'e -o8ni-e to thi approach are that the re'a& 8i'' be temporari'&out of erice 8hi'e etting are automatica''& change-, an- re'a& prob'em that cou'- occur

    -uring the etting change proce cou'- be -ifficu't to -etect9

    ;t 8a mentione- that generator or tranformer outage can ignificant'& impact the amount

    of groun- fau't current in an area9 ;n fact, generator an- tranformer are the motinf'uentia' po8er &tem e'ement 8ithin a 'oca' area that can affect groun- fau't current9

    %he ne?t ection e'aborate on the importance of thi ub/ect9

    >910 Groun- Source ;ue9

    >91091 S&tem Mo-e'

    When performing groun- fau't ana'&i, it i important to erif& the accurac& of the &tem

    mo-e' an- groun- fau't ource in the imme-iate area9 :rror can eai'& be oer'ooke- an-

    there can be a ten-enc& to p'ace b'in- faith 8ith the mo-e' an- -ee'op etting that arebae- on inaccurate fau't a'ue9 %he M(. rating an- impe-ance of tranformer that

    proi-e a ource of groun- fau't current hou'- be erifie- againt ubtation one)'ine

    -ra8ing9 Win-ing connection an- &tem groun-ing hou'- a'o be erifie- againt the

    ubtation -ra8ing9 #'oe attention hou'- be pai- to the accurac& of three)8in-ingtranformer an- auto)tranformer 8ith -e'ta tertiar& 8in-ing9 PSR# WG D i

    -ee'oping a report that -icue mo-e' a'i-ation9

    >91092 S&tem Groun- Source an- their importance to8ar- the contribution of fau't current9

    "ormann Ficher$

    With the gro8ing inf'uence of 8in- an- -itribute- generation in the po8er &tem it ma& be

    a goo- time to e?amine 8hat inf'uence thee hae on the fau't current an- fau't current

    -itribution in a po8er &tem9 ;n thi ection 8e are particu'ar'& interete- in ho8 the non

    conentiona' ource affect the magnitu-e of the groun- fau't current in the po8er &tem,

    Page 1I of 2>

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    -uring a groun- fau't con-ition o that proper co)or-ination bet8een groun- oercurrent

    -eice can be maintaine-9 %o -o thi 'et u ue an e?amp'e &tem a ho8n in Fig ?919

    Fig x.1 A sketch of a simplistic power system

    9 For a groun- fau't at the 'ocation ho8n in Fig9?91 8e can -ra8 the =ero e

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    the ma?imum groun- fau't current for a ing'e 'ine to groun- fau't "'o8et =ero e

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    >911 egatie SeE20 k( autotranformer9 %he aai'ab'e phae fau't current8ere appro?imate'& the ame a the ma?imum tranformer rating, o that phae #

    e'ement a backup protection 8ere of

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    negatie an- =ero e

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    >9119 %appe- Loa- .ffect

    %here are ituation in 'e popu'ate- region 8here tranmiion 'ine are ue- to ere

    io'ate- -itribution ubtation a 8e'' a tranferring energ& from po8er p'ant to ma/or

    'oa- center9 Where thi i -one it i common to app'& three 8in-ing tranformer in the-itribution ubtation, 8&e 8&e 8in-ing 8ith a -e'ta tertiar& 8in-ing9 .n e?amp'e

    8ou'- be to ue a 20k( tranmiion 'ine to erice a 49>k( -itribution &tem9 %he

    o'tage of the tertiar& 8in-ing, 8hich in man& cae i not brought out of the tranformertank, arie from one tranformer to another an- i not re'eant to thi -icuion9 %here are

    no tranmiion 'ine breaker at the -itribution ubtation9 ;n ome cae the fau't

    interrupting -eice, that connect the tranformer to the 'ine, hae rating 8hich re

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    $ References% &i'lio(rap)y

    .'e?an-er,G9 :9, .n-richak, *9 G9, @Groun- Ditance Re'a&ing! Prob'em an- Princip'eA,G:R)J, Genera' :'ectric #o9, preente- at the ineteenth .nnua' Wetern Protectie

    Re'a& #onference, Spokane, W., ct9 20, 1JJ19

    +'ackburn, *9 Le8i,%rotecti"e &elaying %rinciples and Applications, r-e-9, #R# Pre,


    #a'ero, F9 an- ou, D9, @Practica' #oni-eration for Sing'e)Po'e)%rip Line)Protection

    SchemeA, Sch8eit=er :ngineering Laboratorie, ;nc9, 20049

    @#oni-eration in Setting ;ntantaneou ercurrent Re'a& on %ranmiion Line,A

    ;:::EPSR# Working Group Report, ;::: %ranaction on Po8er De'ier&, (o'9 14, o9 1,

    *anuar& 1JJJ9

    Ficher, 9 an- ou, D9B @Metho- for Detecting Groun- Fau't in Me-ium (o'tage

    Ditribution Po8er S&temA, Sch8eit=er :ngineering Laboratorie, ;nc9, Pu''man, W.,2009

    Griffin, #9 9B @Princip'e of Groun- Re'a&ing for igh (o'tage an- :?tra igh (o'tage

    %ranmiion LineA, preente- at the ;::: Po8er :ngineering Societ&, 1JI2 SummerMeeting Paper I2 SM 40)49

    @igh ;mpe-ance Fau't Detection %echno'og&,A ;:::EPSR# Working Group D1> Report,March 1JJ9

    @igh (o'tage %ranmiion Line Protection 8ith Sing'e Po'e %ripping an- Rec'oingA,G:%)>>>, G: Po8er Management, Markham, , #.9

    ou, D9, @Detection of igh);mpe-ance Fau't in Po8er Ditribution S&tem,A Sch8eit=er:ngineering Laboratorie, ;nc9, Pu''man, W., 2009

    '((( )uide for %rotecti"e &elay Applications to ransmission *ines, ;::: #911)1JJJ9

    *ackon, +et, an- +ergen, @.pp'ication of a Sing'e Po'e Protection Scheme to a Doub'e)

    #ircuit 20 k( %ranmiion LineA, >2n-.nnua' Georgia %ech Protectie Re'a&ing#onference, .t'anta, G., 1JJI9

    Mi''er, *9 W9, Preentation entit'e- @.pp'ication of Directiona' Groun- ercurrentRe'a&ingA, Georgia Po8er #ompan&, Foret Park, G., 20009

    Moone&, *9 +9, Peer, *9 M9, @.pp'ication Gui-e'ine for Groun- Fau't ProtectionA, Sch8eit=er

    :ngineering Laboratorie, ;nc, Pu''man, W.,1JJ9

    Page 24 of 2>

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    Sch8eit=er, :9 9, Robert, *9, .rora, R, an- Poggi, :9, @Limit to the Senitiit& of Groun-

    Directiona' an- Ditance ProtectionA, preente- at the Penn&'ania :'ectric .ociation

    Re'a& #ommittee, 1JJ Spring Meeting, .''ento8n, P., Ma& 1>)1, 1JJ9

    Wetern :'ectricit& #oor-inating #ounci', Re'a& Work Group, @Preention of Senitie Line

    Protection egatie Se