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Transformer Stability Test

This document summarizes procedures for testing the stability of transformer differential and restraint relays. It provides test voltages and currents for the high and low sides of a 30MVA transformer. The procedures include creating a fault outside the transformer differential zone and measuring currents on the high and low side CTs. Results showed that the differential and restraint relays operated as expected by indicating differential currents.

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Hemanth Kumar Mahadeva
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© Attribution Non-Commercial (BY-NC)
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14K views4 pages

Transformer Stability Test

This document summarizes procedures for testing the stability of transformer differential and restraint relays. It provides test voltages and currents for the high and low sides of a 30MVA transformer. The procedures include creating a fault outside the transformer differential zone and measuring currents on the high and low side CTs. Results showed that the differential and restraint relays operated as expected by indicating differential currents.

Uploaded by

Hemanth Kumar Mahadeva
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOC, PDF, TXT or read online on Scribd
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Transformer Stability Test

Transformer Details Rated Power Vector Group Rated Vo ta!e "V Rated &urrent "V &T Rat)o "V Rated Vo ta!e +V Rated &urrent +V &T Rat)o +V

30 Mva Dyn1 115 #v 150.'1 A(p. 400*5 13.% ,V 1$55.1 A(p. $000*5

% Impedance 30 mVA base At Tap-1 14.50 % At Tap-9 14.00 % At Tap-$1 13.%0 %

HV Voltage At Tap-1 At Tap-9 At Tap-$1

1$'.5 #v 115 ,V 9-.-5 ,V

Tap-9 ). no()na tap o/ t0e tran./or(er. Procedure for Transfer Stability Differential Relay as ell as R!" Relay Stability App y 3-p0 3%0 Vo t. at t0e Pr)(ary .)de o/ t0e Tran./or(er and 1"2RT a t0e T"R33 P"A13 +V a/ter D)//erent)a &T.. App )ed Vo ta!e )n Pr)(ary 1)de 3%0 V 34pected "V 1)de &urrent 5 5 5 App )ed Vo ta!e 4 "V &urrent 6At Tap-97 % 8(pedance 4 Vo ta!e o/ t0e Tap 3%0 4 150.'1 0.14 4 115000 3.554 A(p..

34pected 1econdary &urrent o/ ")!0 .)de &T 5 3.554 4 5 400 5 34pected +V .)ded &urrent 5 5 0.044 A(p.. App )ed Vo ta!e 4 +V &urrent #At Tap$%& % 8(pedence 4 Vo ta!e o/ t0e Tap 3%0 4 1$55.1 0.14 4 115000

5 $9.'$ A(p.. 34pected 1econdary &urrent o/ +ow .)de &T 5 $9.'$ 4 5 $000 5 0.0-40 A(p..

9ow: /or c0ec,)n! o/ Tran./or(er 1TA;8+8T<: you 0ave to create a /au t on out.)de o/ t0e D)//erent)a &T..

R Y B High Side CTs HV Breaker

Transforme r Neutra l CT LV Breaker Low Side CTs


)reate a "A*+T ,ere-

A/ter t0).: (ea.ure t0e current o/ ")!0 1)de &T. and +ow 1)de &T. )n a t0e (ea.ura= e po)nt. ),e >T.: A((eter: D)//. Re ay: R3> Re ay etc. Result' 1. D)//. Re ay .0ou d not operate. $. R3> Re ay .0ou d not operate. Differential as ell as R!" Sensiti(ity Test

)reate a "A*+T ,ere-

R Y B High Side CTs HV Breaker


)reate a "A*+T ,ere-

Transforme r Neutra l CT LV Breaker Low Side CTs


A/ter t0).: (ea.ure t0e current o/ ")!0 1)de &T. and +ow 1)de &T. )n a t0e (ea.ura= e po)nt. ),e >T.: A((eter: D)//. Re ay: R3> Re ay etc. Result' 1. D)//. Re ay .0ou d .0ow D)//erent)a &urrent. $. R3> Re ay .0ou d .0ow D)//erent)a &urrent.

Same

ay you ,a(e to do for remaining P,ases-

<ou can create: 3-p0 ? G /au t )n pace o/ do)n! )nd)v)dua : depend. on re@u)re(ent.

R!" Stability Ae a ready c0ec,ed w0) e do)n! Tran./or(er D)//erent)a 1ta=) )ty: =ut 8 a( d).p ay)n! 0ere anot0er way to do R3> .ta=) )ty P0a.e =y P0a.e.

R Y B High Side CTs HV Breaker

Transforme r Neutra l CT LV Breaker Low Side CTs


)reate a "A*+T ,ere-

Result' 1. R3> Re ay .0ou d not operate.

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