Answer Posted / tomson philip

REF Protection- There may be number of feeders down-
stream on the T.F.So if an earth fault occurs in one
of such feeders, that fault should not disturb the
transformer.If the transformer is not protected with REF
what happens is, everytime there is a fault some where
on it's feeders,the T/F will trip and all feeders will
be affected. This will go on happening from feeder to
feeder and consumers get in to trouble unnecessarily. But
with REF ,the transformer will trip only when there is
earthfault within T/F itself, which very very seldom
only occurs.In other words T/F tripping restriced to fault
within cases only.But the case of out-going feeders is
not so safe as to avoid earth fault.They may be in
a jungle where tree branches can touch the conductor
and cause a tripping.So T/F with REF will not trip in
such situation and power interruption will be only in
the feeder affected.

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