Interested to Buy Any Domain ? << Click Here >> for more details...
WHY IS RESTRICTED EARTH FUALT PROTECTION NEEDED?? WHY CANT
DEIFFERENTIAL PROTECTION SUFFICE???
- 14 Answers
- 28962 Views
- I also Faced
- E-Mail Answers
Answer Posted / akshit limbasiya
A Restricted Earth Fault (REF) means an earth fault from a
restricted/localized zone of a circuit.
The term "REF protection method " means not to sense any
earth faults outside this restricted zone.
REF is a type of "unit protection" applied to transformers
or generators and is more sensitive than the method known as
differential protection.
An REF relay works by measuring the actual current flowing
to earth from the frame of the unit. If that current exceeds
a certain preset maximum value of milliAmps (mA) then the
relay will trip to cut off the power supply to the unit.
Differential protection can also be used to protect the
windings of a transformer by comparing the current in the
power supply's neutral wire with the current in the phase
wire: if the currents are equal then the differential
protection relay will not operate; if there is a current
imbalance then the differential protection relay operates.
However, REF protection is also applied to transformers in
order to detect ground faults on a given winding much more
sensitively than differential protection can do.
| Is This Answer Correct ? | 2 Yes | 1 No |
Post New Answer View All Answers
i want to put single phase load on scott connected transformer,eventhough how to balance the transformer.
How will polarity test of Dy5 Transformer ?
Power factor =1.000 at factory in supply. However, PF = 0.8 at motor end. Current = 100 Amp, Voltage = 400 V. What is the power distribution loss? Can I reduce it by adding capacitor at the load feeder?
What is voltage divider rule?
for compensate 315mh inductance ,how many capaciance required?
why Induction Generators are not "Black start" ? and apart from WTGs where this types of generator are generally used?
what are the factors to be considered while design the breaker either HT or LT??
as a electrical student why should i hire you?
static chagre
State the frequency for rc phase shift oscillator?
The knee point of a current transformer is normally unique and known.So why in the nameplate of a CT they put the minimum value like this Vk> 400v.
What is the ratio of true power to apparent power in an ac circuit?
what is is the potential diffrence between two phase ?
how to find out 3 phase complex power in per unit in unbalanced system?
What are the advantages of a three-phase system over a single-phase system?
