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What is the function of restraining coils in differential relay?
Aneesrehman
Restraining coils are also called as bias coils. Due to the difference in the magnetizing currents of the upper and lower current Transformers the current through the operating coil will not be zero even under normal loading conditions or external fault conditions. therefore to provide stability on external faults bias coils are provided. To obtain the required amount of biasing a suitable ratio of the biasing coils with restraining coils to be provided.
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∙ 15y ago
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What is the definition of differential relay and how does it function?
In power transformer, a differential relay is a relay that verifies the balance of current between the primary and the secondary face of a transformer. It is also employed in other components of the power system like in protecting cables. Differential relay is also called a unit protection.
What is function of mho relay?
OFFSET IMPEDANCE RELAYOffset impedance relay is also known under names ADMITTANCE RELAY or MHO RELAY
Will a transformer Differential Relay act online to line to fault?
, The zone of protection for 2 , 3 or multi windings transformers differntial relay is decided by the location of CT.s at the respective sides i.e. HV. IV OR LV SIDES . Ideally on any fault within zones of these C.T.s the differential relay should act. However sometimes inadequecy of C.T. s ratings like low burden rating, less knee point voltage or improper biased settings may cause the differential relay to operate even on line faults. Regards, J.M.SHAH
Is a relay considered a load?
The relay's coil(s) would be a load, but the main function of a relay is to act as a switch to control power to a larger load.
What is a function of a Buchholz relay?
A Buchholz relay is designed to detect a failing oil-filled power transformer. It will automatically disconnect the transformer and produce an alarm signal.
What is ment by restraining coil?
straining coils are winding that we uses to prevent the fault operation of relay
What is percentage bias relay?
This is basically a differential relay that contains an additional restraining coil with the operating coil connected at its midpoint used to prevent the unnecessary pick up of the relay.
What is the definition of differential relay and how does it function?
In power transformer, a differential relay is a relay that verifies the balance of current between the primary and the secondary face of a transformer. It is also employed in other components of the power system like in protecting cables. Differential relay is also called a unit protection.
What is differential relay?
when the cable of a motor shorted then differetial relay act
Which relay is used to protect generators and motors?
differential protection relay
What is motor differential relay?
when the cable of a motor shorted then differetial relay act
Dear all what direct consequences can be from Current transformer on generator with respect to differential protection relay?
CT's are used as inputs to the differential. If the CT is bad, or it is not wired to the differential correctly, it will cause differential current to be seen by the relay, resulting in a trip.
What is function of static relay?
function of static relay
What is the function of static relay?
function of static relay
Where you can see differential protective relay?
Power Transformer
Why percentage differential protection is preferred over differential protectionfor internal faults?
if we are seeking for internal protection of transformer only, then if any external fault occurs then it will show the fault though it should not. what a percentage differential protection will do means, it will include a restraining coil which is excited by the current in the transformer itself. Also the percentage differential relay ha taps. So it is easy to avoid the external fault. for reference check 'theory and applications of transformer differential protection' by GEORGE W.McKENNA, AIEE transactions 1950,volume 69
What is operating coil of differential relay?
My understanding is that on most (if not all) differential relays, there are currents coming in from both sides of the operating coil. These currents should cancel out, or in reality, nearly cancel out. Therefore, the effective current in the operating coil is zero. When the net current in the operating coil is not zero, the relay trips. There are instances when you don't want the relay to trip though. Therefore, the operating coil works together with a restraint coil. (Well probably 2 restraint coils.) The relay will trip if the operating coil's current must exceed the restraint coil's current by a certain amount.
