what is the diff. b/w restricted earth fault relay &
standby earthfault relay and where they are used?
Answer Posted / shirish prajapati
The REF and SBEF are two separate protection functions. The
REF will protect the transformer winding and the cables to
the breaker. SBEF is standby earth fault protection. It is
backup protection in case of uncleared faults out on the
network, or earth faults outside the REF zone. It may also
protect the neutral earthing resistor if there is one, and
may act as a cheap busbar protection system by tripping the
LV bus section first and the transformer LV C/B second. Do
you really want to compromise important backup protection
for the cost of a neutral CT? You have the option to get
another CT fitted in the bushing, or if there is a neutral
cable terminated on the bushing you could install a slipover
CT on the cable, or in the NER cable box. Lots of
possibilities, and not very expensive.
| Is This Answer Correct ? | 31 Yes | 8 No |
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