Answer / badshah

In an rccb when current more than the prescribed value is
induced then the secondary coil of the relay trips the
elcb. for example if a heater is connected in a circuit
and when the resistance i.e the megger value of the heater
body to the earth is less and if more current flows through
the ciruit and the earth then the elcb or the rccb trips to
protect the circuit. earth leakage is something when there
is an imbalance of load in each phase in a 3 phase circuit
and where u can measure a voltage or impedence between the
neutral and the earth.

Answer / narottam pradhan

The relay which protect the equipment/system by disconnecting supply when a earth fault occures in direct grounded system of power supply is called earth fault relay.In case of restricted earth fault relay the magnitude of earth fault current is limited to a specified value by employing suitable designed restricted neutral system of power supply.

Answer / rv

ref- this protection is designed to look back towards the
secondary windings of the suppl transformer and all small
control wiring and other current transformer.
while earth leakage relay is designed to protect the
circuit in the unit.

Answer / dolphin

earth leakage relay sense leakage current using troide
around 5 wires (R,S,T,N,E) or earth wire only and give its
signal for protection relay which protect this power cable
feeder.
restricted earth fault make protection for predifined and
determined zone, always protect primary or secondary of
transformer or both of them through no. of 3 ct at power
lines and 1 ct at star point of transformer which connected
to earth so it protect winding of transformer and zone till
ct's.

Answer / ali alhawarey

earth fault leakage relays are designed to work for any
fault related with earth i.e it can protect the whole
winding but since we use differntial protection no need for
this because differntial protection can protect the winding
up to certian limit
for faults far from the neutral point the leakage current
is high enough for differential protection tripping

for faults near the neutral point the fault voltage is small
nd so currents the differential protection will not operate
this area is coverd by restricted earth fault

Answer / alialewesy

earth leakage relay can not distinguish the fault location
so that it works for faults inside transformer winding &
outside transformer winding ( drawback)
REF protection has the advantage of distinguishing the
fault location .
it works only for earth faults inside the transformer
winding the transformer will be tripped only for earth
fault insid their winding
th only disadvantage of REF protection is that
it can not cover the whole winding . it protect only 80-85%
of transformer winding
for the reason of CT differences & saturation of CT
so that astand by protection is needed to protect the 15%
of the unprotected winding

Answer / pradeep mishra

basic diference between earth leakage relay and restricted
earth fault relay, earth leakage relay used in under ground
mines and restricted earth fault relay used in open cost
mines

Answer / lokesh ranjith

The earth leakage relay detect the leakage current in the
CBCT, also earth leakage relay activates when hormonics
levels increased,

when ever the phase touches the ground, restricted earth
fault relay will get activated

Answer / k.rajmohan

The main difference between these two is the zone is
restricted in REF. There is zone restriction for Earth
leakage relay.

Answer / rahul

EARTH LEAKAGE RELAY IS USED FOR DETECTION OF EARTH LEAKAGE
WHICH WORKS ON THE PRINCIPLE OF SENSING THE CURRENT FLOWING
THROGH THE LIVE WIRE. A SIMPLE COMPARATOR CAN BE USED WHERE
ONE INPUT OF THE COMPARATOR IS FED IN WITH SOME CALCULATED
REFERRENCE VOLTAGE AND THE SECOND INPUT OF THE SAME
COMPARATOR IS CONNECTED TO THE LIVE LINE, WHICH ON THE
OCCURENCE OF EARTH FAULTS, WILL DELIVER HIGH VOLTAGE
(GREATER THAN THE REFERRENCE VOLTAGE)AND HENCE, O/P OF
COMPARATOR BECOMES HIGH-LOGIC.....WHICH FURTHER CAN BE USED
FOR TRIPPING THE I/P POWER NY APPLYING SOME TRANSISTOR
BIASING LOGIC OR BY APPLYING SOME CONTROLLER-LOGIC.....
NOTE:- IT IS NOT USED TO MONITOR THE CURRENT AT NEUTRAL
LINE.....

WELL, THIS IS 100% CORRECT AND I KNOW ABT EARTH LEAKAGE
RELAY ONLY, I DON KNOW ABT THE OTHER TYPE.

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