MKA IDMT Overcurrent Relay User’s. Guide. A BRIEF OVERVIEW a b c d h g f e a – Auxiliary power supply indicator b – High-set start/trip status indicator. OVERCURRENT RELAY WITH IDMT. ○ Test and reset facility. ○ Convenient C. T. connections. ○ Double pole double throw 10A VAC Relay Output. Setting calculation is separated for overcurrent and eart fault relay with input parameters: Name of Feeder, Load Current: (IL) in Amps, Min Fault.

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A piece of iron is so fitted by hinge support and restraining spring in the relay, that when there is not sufficient current in the coil, the NO contacts remain open.

Le Xuan Binh Jan 08, The other terminology used for overcurrent is overcrrent and low-set.

Types and Applications Of Overcurrent Relay (part 1)

Unit type schemes protect a specific area of the system i. Extremely Inverse Relay is one in which CT saturation occur still at a later stage as compared with Very Inverse Relay and hence the characteristic remain inverse up to a larger range of fault current.

Inverse Time Over Current Relay Inverse time is a natural character of any overcurreht type rotating device.

Although time inverse characteristic is inherent to electromechanical induction disc relay, the same characteristic can be achieved in microprocessor-based relay also by proper programming.

Definite Time Over Current Relay This relay overcyrrent created by applying intentional time delay after crossing pick up the value of the current. Please develop the app at most and website too….

Following are the important features of an Icmt Over-current Relay: He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. Over-current Relay gives protection against: September 25, at There is only one current operated element in the relay, no voltage coil etc.


Ibrahim Kurdi Feb 19, The overcurrent protection is a bigger concept So that the overload protection can be considered as a subset of overcurrent protection. Mathieu Lachane Jun 24, That is why the relay is referred as inverse definite minimum time over current relay or simply IDMT relay. The protection should not operate for starting currents, permissible overcurrent, current surges.

September 25, at 6: As the relay current does not increase further, there would not be any further reduction in time of operation in the relay. Thanks alot for the helpful information you provide.

The content is copyrighted to EEP and may not be reproduced on other websites. Overcurrent protection protects electrical power systems against excessive currents which are caused by short circuits, ground faultsetc.

In this type, two conditions must be satisfied for operation trippingcurrent must exceed the setting value and the fault must be continuous at least a time equal to time setting of the relay. Working Principle of Over Current Relay In an over current relaythere would be essentially a current coil.

Idnt definite minimum time IDMT over-current Relay is one in which the operating time is approximately inversely proportional to the fault current near pick-up value and then becomes constant above the pick-up value of the relay. These ratings include overcurrnt, ampere and interrupting rating. While, the overload protection protects against the situation where overload current causes overheating of the protected equipment.

The uncertainty of the operating time and the necessary operating time may require a grading margin of 0. Notify me when new comments are added.


Over Current Relay Working Principle Types

There are standard inverse, very inverse and extremely inverse types. First of all i would like to thanks you very very much, idt lesseon are so valuable To introduce myself, my name Binh, i am Vietnamese, i work for shipyard that many electrical issue i met everyday make me many questions about it. Please suggest us to reduce these frequent tripping of relay, what will be the characteristics of relay to be set definite time, normal inverse or very long inverse etc.

Oveecurrent of protection Protection schemes can overcrurent divided into two major groupings: Felay time of operation of such Relay is approximately ms. Current limiting can be considered as another overcurrent protective device rating, although not all overcurrent protective devices are required to have this characteristic.

Any deviation from this must indicate an abnormal current path. This is the simplest of the ways to protect a line and therefore widely used. But when the current through the coil increases, the magnetic effect increases, and after a certain level of current, the deflecting force generated by the magnetic effect of the coil, crosses the restraining force.

Over Current Relay Working Principle Types

From the picture, it is clear that there is some definite time after which the Relay will operate. Definite time over current relay. Instantaneous, in old days used to be high set i.