What is CDG relay?
Type CDG 11. Overcurrent and Earthfault Relay. General description. A non-directional heavily damped induction disc relay which has an adjustable inverse time/current characteristic with a definite minimum time. The relay has a high torque movement combined with low burden and low overshoot.
Which type of relay is earth fault relay?
It is a directional relay. Earth fault relay responds to fault in which power flow is in the set direction from the CT and PT locations. Thus, directional relays are used when power can flow from both directions to the fault point.
How does an earth fault relay work?
Earth Fault relays In case of phase to ground faults, high currents flow to the grounded neutral of the transformer. Earth fault relay senses these faults. Usually, the contacts of the earth fault relay are connected to the trip circuit of circuit breakers at the output side of the transformer.
What is an IDMT relay?
IDMT relay is inverse definite minimum time relay. It is one in which Time of operation is inversely proportional to magnitude of fault current near pickup value and becomes substantially constant slightly above the pickup value of the Relay.
What is non directional earth fault?
The directional or non-directional earth-fault relay REJ 517 is a secondary relay which is connected to the voltage and current transformers of the object to be protected.
Which restricted earth fault relay is restricted to?
The earth fault relay operates only for the internal fault of the protective zone. The earth fault relay must be very sensitive for sensing the fault. The relay is designed for sensing the fault current which is 15% more than that of the rated winding current. Such settings protect a restricted portion of the winding.
What is reverse power relay?
Reverse Power Relay is a directional protective relay that prevents/protect the generator from motoring effect (going to reverse direction). It is used where generator runs in parallel with other utility or generator.
What is mean by inverse characteristics of relay?
Inverse Time Relay An inverse-time relay is one in which the operating time is approximately inversely proportional to the magnitude of the actuating quantity. The figure shows the time-current characteristics of an inverse current relay. At values of current less than the pickup, the relay never operates.