Transformer Stability test

Transformer Stability Test Transformer Details Rated Power

30 Mva

Vector Group

Dyn1

Rated Vota!e "V Rated &urrent "V

115 #v 150.'1 A(p.

&T Rat)o "V

400*5

Rated Vota!e +V

% Impedance 30 mVA base At Tap-1

14.50 %

At Tap-9

14.00 %

At Tap-$1

13.0 %

HV Voltage

Rated &urrent +V

13. ,V 1$55.1 A(p.

&T Rat)o +V

$000*5

At Tap-1

1$'.5 #v

At Tap-9

115 ,V

At Tap-$1

9.5 ,V

 Tap-9 ) no()na no()na tap o/ te tran/or(er. tran/or(er. Procedure for Transfer Stability Differential Relay as ell as R!" Relay Stability Appy 3-p 30 Vot at te Pr)(ary )de o/ te Tran/or(er and "2RT a te T"R P"A +V a/ter D)//erent)a &T. App)ed Vota!e )n Pr)(ary )de 30 V pe pect cted ed "V )de )de &urr &urren entt



App)ed Vota!e  "V &urrent 6At Tap-97 % 8(pedance  Vota!e o/ te Tap



30  150.'1 0.14  115000



3.554 A(p.

pected econdary &urrent o/ ")! )de &T  3.554  5 400

pected +V )ded &urrent



0.044 A(p.



App)ed Vota!e  +V &urrent #At Tap$& % 8(pedence  Vota!e o/ te te Tap



30  1$55.1 0.14  115000

 $9.'$ A(p. pected econdary &urrent &urrent o/ +ow )de &T  $9.'$  5 $000 

0.040 A(p.

ow: /or cec,)n! o/ Tran/or(er TA;8+8T<: you ave to create a /aut on out)de o/ te D)//erent)a &T.

R  Y B High Side CTs HV Breaker 

Transforme r  Neutra l CT LV Breaker 

)reate a "A*+T ,ere-

Low Side CTs

A/ter t): (eaure te current o/ ")! )de &T and +ow )de &T )n a te (eaura=e po)nt ),e >T: A((eter: D)//. Reay: R> Reay etc.

Result' 1. D)//. Reay oud not operate. $. R> Reay ou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 t): (eaure te current o/ ")! )de &T and +ow )de &T )n a te (eaura=e po)nt ),e >T: A((eter: D)//. Reay: R> Reay etc. Result' 1. D)//. Reay oud ow D)//erent)a &urrent. $. R> Reay oud ow D)//erent)a &urrent.

Same ay you ,a(e to do for remaining P,ases 
R!" Stability e aready cec,ed w)e do)n! Tran/or(er D)//erent)a ta=))ty: =ut 8 a( d)pay)n! ere anoter way to do R> ta=))ty Pae =y Pae.

R  Y B High Side CTs HV Breaker 

Transforme r  Neutra l CT LV Breaker  )reate a "A*+T ,ere-

Low Side CTs

Result' 1. R> Reay oud not operate.