REF/NEF Protection
REF/NEF Protection
(OP)
Hi everyone,
I will please like to know if i can use nuetral earth fault protection in place REF in a star Delta transformer.Wnat is the implication of not providing REF protection on Y/D transformer.
I will please like to know if i can use nuetral earth fault protection in place REF in a star Delta transformer.Wnat is the implication of not providing REF protection on Y/D transformer.






RE: REF/NEF Protection
If you have any chance of a ground fault on the star side of the transformer and you expect to ride through it without tripping, then your EF relay must be sufficiently slow to allow other protection to operate and clear the fault. The REF system is designed to provide very fast, sensitive protection for faults within the protected zone, and to be insensitive to faults outside of the protected zone. The plain EF relay will respond to all faults, so by making it sufficiently insensitive or slow to allow it to discriminate with other protection in the event of a fault you inherently have less protection for your transformer. It could prove to be a very expensive decision to omit the fast protection, making the difference between a repair to the transformer and counting the fragments of the transformer.
If you don't care about tripping the transformer for faults out on the system, then by all means use a plain E/F relay but expect nusciance trips to occur. I personally think it would be a very bad idea from both the point of view of system security and of protection of plant. Plain E/F on the neutral is typically used as backup protection for a relay scheme in conjunction with an IDMT relay.
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RE: REF/NEF Protection
If possible, rather stick to REF.
Regards.
RE: REF/NEF Protection
One thing extra, although not compulsory at this moment: Arc flash protection. Many countries do not even think of it now, but in my opinion it will eventually be implemented through-out the world. A fast protective scheme, like REF-protection, will certainly reduce arc-flash hazards. One thing to consider for the future.
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RE: REF/NEF Protection
please, if i must protect my transformer for REF,then can anyone recommend Alstom VCSU earth fault relay for this purpose.
Thanks.
RE: REF/NEF Protection
RE: REF/NEF Protection
Iam sorry, i mean MCSU Alstom type.
RE: REF/NEF Protection
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I don't suffer from insanity. I enjoy it...