Transformer Protection Rev1

7/21/2019 Transformer Protection Rev1

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TRANSFORMER PROTECTION

By

Y. k. Pandharipande.



CLASSIFICATION

1. Protection aain!t E"ectrica" Fa#"t!$nit Protection %aain!t Interna" Fa#"t!&Differential Protection.REF Protection.

Non'$nit Protection %aain!t #nc"eared e(terna" )a#"t!&IDMT O/C, E/F Relays.Definite Time O/C, E/F Relays.

*.Protection aain!t A+nor,a" Condition! Over Load protectionOver Fl!in" Protection

-. Protectie /eice! %Non'e"ectrica"&#c$$ol% &Main Tan' / OLTC(Oil / )indin" Temperatre Indicators / Relays

Pressre Release *alveOil Level +a"es / Indicators





/IFFERENTIAL RELAY 0 OPERATIN PRINCIPLE

C#rrent /i!tri+#tion %E(terna" Fa#"t&

Battery Ana"oy %E(terna" Fa#"t&




/IFFERENTIAL RELAY 0 OPERATIN PRINCIPLE.

C#rrent /i!tri+#tion % Interna" Fa#"t&

Battery Ana"oy %Interna" Fa#"t&




/IFFERENTIAL RELAY 0 NEE/ FOR BIAS

Tran!)or,er ratio 2 13345367 F.L. C#rrent 2 133A %on 133 67 !ide& 2 *33A %on 53 67 !ide& Tap Rane 2 %84'& 139

9 I,pedance %:t& 2 139




/IFFERENTIAL RELAY 0 NEE/ FOR BIAS.

C#rrent /i!tri+#tion on Load on Nor,a" Tap




/IFFERENTIAL PROTECTION 0 NEE/ FOR BIAS

C$RRENT /ISTRIB$TION ON LOA/ ON 8 139 TAP




/IFFERENTIAL PROTECTION 0 NEE/ FOR BIAS.

C$RRENT /ISTRIB$TION ON T;RO$; FA$LT ON 8 139TAP.




/IFFERENTIAL RELAY 0 NEE/ FOR BIAS.

/i)). Pick'#p 2 159 %3.15A&< Bia! 2 -39 %A!!#,ed&

Modi)ied /i)). Pick'#p d#e to Re!trainin E))ect o) Bia!

Id ,od 2 3.-3 ( %138=&4* 8 3.15 2 *.>5 8 3.15 2 -.3A.

Act#a" /i)). C#rrent 2 1.3A




/IFFERENTIAL PROTECTION 0 BIAS C;ARACTERISTIC.




/IFFERENTIAL PROTECTION 0 MANETISIN INR$S;.

STEA/Y STATE At ?ero o"t!< )"#( i! @%'& ,ɸ !ince )"#( in #adrat#re ith o"tae.

Tota" )"#( chane in ha") the o"tae cyc"e i! @* , %' , to 8 ,&.ɸ ɸ ɸ

SDITC;IN AT 7OLTAE :ERO. Initia" )"#( ?ero a! aain!t %'& , corre!pondin to !teady !tate.ɸ

Tota" )"#( chane! )ro, ?ero to * ,.ɸ

F"#( do#+"in ca#!e! e(tre,e !at#ration o) core.




/IFFERENTIAL PROTECTION' MANETISIN INR$S;.

Maneti!in I,pedance dra!tica""y red#ce! d#e to core!at#ration ca#!in heay inr#!h c#rrent.

Inr#!h appear! on e(cited indin %pri,ary& itho#t any+a"ancin c#rrent on !econdary and #n!ta+i"i!e! di))erentia"

protection.




/IFFERENTIAL PROTECTION 0 INR$S; STABILITY

Inr#!h c#rrent ha! predo,inant * nd har,onic content%typica" a"#e< #pto 39 ,a(. o) F#nda,enta" dependin#pon in!tant o) !itchin&.

/o,inant * nd har,onic co,ponent i! #!ed to re!train theprotection on inr#!h condition.




BIASE/ /IFFERENTIAL PROTECTION' INTERNAL CIRC$IT.




/IFFERENTIAL PROTECTION' CT CONNECTIONS.

STAR 4 STAR TRANSFORMER




/IFFERENTIAL PROTECTION 0 CT CONNECTIONS.

/ELTA 4 STAR TRANSFORMER %/y11&




/IFFERENTIAL PROTECTION 0 STAR 4 STAR TRANSFORMER

In!ta+i"ity Dith STAR CONNECTE/ CT! On $p'!trea, Earth Fa#"t.




/IFFERENTIAL PROTECTION 0 STAR 4 STAR TRANSFORMER.

/e"ta 4 /e"ta CT! )i"ter :ero Se. C#rrent en!#re Sta+i"ity.




REF PROTECTION

C#rrent /i!tri+#tion on E(terna" Earth Fa#"t.




REF PROTECTION

C#rrent /i!tri+#tion on Sin"e Pha!e "oad.




REF PROTECTION

C#rrent di!tri+#tion on Interna" Fa#"t.




STABILISIN RESISTOR

SETTIN CRIETERIA

I) B' CT )#""y actie hi"eɸ

NCT )#""y !at#rate!< ,a(i,#,

7o"tae acro!! Re"ay Branch

%7!& 2 I)4n %Rct 8 *R"&.

I) Re"ay c#rrent !ettin i! @I!

and Oh,ic +#rden i! @:r< Sta+. Re!i!tor Settin %R!&

2 7!4I! 0 :r Oh,!.




BAC6$P PROTECTION

INFL$ENCIN FACTORS

7ector ro#p

In)eed condition! %Sin"e or +oth end in)eed!&

Type o) Ne#tra" Earthin




BAC6$P PROTECTION

LEEN/ 53 0 ;ih Set In!t. O4C Re"ay % /e"ta !ide S.C. protection&

G 0 REF Protection %/e"ta !ide REF protection&

51 0 I/MT O4C Re"ay %ti,e raded +ack#p )or don'!trea, S.C.&

51N 0 I/MT E4F Re"ay %ti,e raded +ack#p )or don'!trea, E4F&




BAC6$P PROTECTION

E4F PROTECTION ON /ELTA SI/E.

/e"ta !ide E4F re"ay inherent"y i,,#ne to Star !ide earth)a#"t! +#t can re!pond to /e"ta indin earth )a#"t!. ;ence!en!itie< hih !peed E4F re"ay %G& in ;ih I,pedance ,odecan +e #!ed on /e"ta !ide.




BAC6$P PROTECTION

LEEN/ 53 0 ;ih Set In!t. O4C Re"ay %Pri,ary Star !ide S.C.&

51' I/MT O4C Re"ay %ti,e raded +ack#p )or don'!trea, S.C.&

HN 0 /irectiona" I/MT E4F Re"ay %+ack#p toTFR4don'!trea, E4F.&

51N0I/MT E4F re"ay %ti,e raded +ack#p aain!t don'!trea, E4F&




BAC6$P E4F PROTECTION' STAR 4 STAR TRANSFORMER

/irectiona" I/MT E4F re"ay %HN& "ookin toard!tran!)or,er do not re!pond to #p'!trea, E4F d#e toc#rrent o#t')"o )ro, TFR ter,ina" into rid< th#!re#irin co'ordination ith don'!trea, E4Fprotection! on"y.




O7ER LOA/ PROTECTION

1. /e)inite Ti,e Oer Load Re"ay

/e)inite Ti,e O4C re"ay #!ed )or A"ar,.

Set a+oe per,i!!i+"e oer "oad ith !,a"" ti,ede"ay%!ay 5 !econd!&

Re"ay !ho#"d hae ad#!ta+"e c#rrent !ettin< ti,e de"ay%+#i"t'in or e(terna"& and hih re!et ratio.

So,e ti,e!< e(tended trippin i! proided ithadditiona" ti,e de"ay.




O7ER LOA/ PROTECTION

*. Ther,a" Oer Load Re"ay

Set to ,atch oer "oad ith!tand o) tran!)or,er.

Pre'trip A"ar, ith "oer pick'#p thre!ho"d.

Operatin ti,e )or trip %t&

t 2 T. "n J%I46.In&K 0 %I pre46.In&K 4 %I46.In&K' 1

DhereI 2 Oer Load c#rrent.

6.In 2 Ma(. Per,i!!i+"e Load C#rrent.

I pre 2 Load c#rrent prior to Oer Load.

T 2 Ther,a" Ti,e Con!tant %,in#te!&




O7ER FL$IN PROTECTION

IN/E OF O7ER FL$IN

7 .)< ;ence 74)

Tande, ariation! in o"tae )re#ency ,o!t"ike"y to occ#r in ca!e o) enerator Tran!)or,erd#rin !tart#p or coa!tin don %d#e to A7R,a")#nction or ,an#a" contro"& re#irin OerF"#(in Protection.

It i! nece!!ary )or rid TFR! a! e""< #nder certaincondition! %e.. TFR )ed +y "on tran!,i!!ion "ine!#+ected to hih o"tae d#e to Ferranti E))ecthen o))'"oaded&.




O7ER FL$IN PROTECTION

1. /e)inite Ti,e Oer )"#(in re"ay.

Ad#!ta+"e 74) !ettin %typica""y 1 0 1.5 o) 1137 4 53;?&.

Ad#!ta+"e trip ti,e de"ay %typica""y 13 0 1*3S&

Pre'trip A"ar, %)i(ed or aria+"e de"ay&

*. I/MT Oer F"#(in Re"ay

Ad#!ta+"e 74) !ettin. Iner!e ti,e characteri!tic to ,atch ith TFR ith'

!tand characteri!tic.

Pre'trip A"ar, and acce"erated trip )or !eere oer)"#(in condition.




BAC6$P EART;FA$LTPROTECTION

− NCT operatedStand+y E4F

Re"ay re!pond! tointerna" earth)a#"t! a! e""<+e!ide! proidin+ack#p aain!te(terna" )a#"t!.

− Stand +y E4F re"ayo))er! +etter

!en!itiity !inceNCT ratio not tied#p ith "oad and"oer ratio< +a!edon E4F in)eed!< i!po!!i+"e.

Transformer Protection Rev1

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