What is the difference between idmt and dmt

As the current increases, the relay requires a minimum time to stop the circuit. Definition: A dependent time delay relay having an operating time which is an inverse function of the electrical characteristic quantity. 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. Both have different saturation levels. The working of the relay depends on the electrical components.

The relay has less overloading capacity. The static relay is more costly as compared to the electromagnetic relay. The construction of the relay is easily affected by the surrounding interference.

If A current flows for time Td, the relay will operate to change its output contact status. This is shown in figure above. Let us make this clearer. Suppose the set time delay Td is ms. Does this means that the relay will give tripping command after ms after sensing the overcurrent in the circuit?

Is this interpretation correct? No, this is not correct interpretation. The actual interpretation is that the overcurrent in the protected circuit must remain for ms for Definite Time Overcurrent Relay to operate.

See the curve, the curve become vertical straight line, since the relay does not have any time delay. Save my name, email, and website in this browser for the next time I comment. Difference Protection. What is Arc Chute? Types, Working Principle [Video Included].

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