What are the possible causes of REF operation on a power
transformer

Answer Posted / k.prakashchandra

All cts(Phases and neutral) are connected in parallel.If
there are unbalanced currents in phases, the resultant
current in REFR is zero as the difference is also measured
by NCT .If there is an earth fault inside the transformer
or between cts and bushings ,the fault current is sensed by
NCT only. Hence current balnce is lost in REFR resulting in
trip command by the relay

Is This Answer Correct ?    3 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

What do you mean by Stimulastion Test in Diesel Genarator / Why & when it's conducted ?

1215


advantage of motor design on higher power factor . normally motors are designed for .8 power factor. what is advantage of designing at .88 power factor

1394


Why did lightening arrestor solid copper rod head is sharp on mobile tower top?

1544


In 90 kva alternator that produce the output voltage is 115(p-n),200(p-p) at 1500 rpms means what ampere it produced ?

1602


Why does inductive loads consume KVARs?

1562






how many parameters can integrate with fire alarm basically ?

1497


How to maintain ac plant?

1530


can we synchronize star system generators with delta system transmission line ? and how ?

2313


Can you explain about TEE protection scheme?

1761


how dia of wire and angles are calculated for overhead shielding wire to protect substation equipment from lightening strokes???

1574


How can get elongation of 2 k.G aluminium, if elongated aluminium dia is 2.5 mm?

1824


does the Trivector Meter of three phase automatically takes care of the low power factor and gives the reading accordigly or it does not take care of the Power factor while giving the readings please explain

1407


What is the effect of pi controller on the system performance?

615


WHAT IS FAULT CAPACITY OF HT MOTOR TERMINAL BLOCK? ANY BODY HAVE ANSWER PLZ....POST IT.

1718


What is Load sharing of Transformer ?

1550