Overload Relay Working Principle Pdf

As explained above a bimetallic thermal relay works on heating property of bimetallic strip.

Overload relay working principle pdf. In an over current relay or o c relay the actuating quantity is only current there is only one current operated element in the relay no voltage coil etc. The bimetal strips are heated by the motor current causing them to bend and activating the trip mechanism after a certain travel which depends on the current setting of the relay. Read more thermal overload. Hi friends in this article i am talking about thermal overload relay working principle and its function in a dol starter.

An overload relay switch works in characteristics with current over time and is different from circuit breakers and fuses where a sudden trip is made to turn off the motor. I hope you will find this article informative and helpful. Fundamental relay operating principles and characteristics 17 time delay and its definitions some relays have adjustable time delay and others are instantaneous or high speed the term instantaneous means having no intentional time delay and is applied to relays that operate in a minimum time of approximately 0 1 second. Excess current will cause the overload relay to trip at a predetermined level opening the circuit between the power source and the motor.

Working principle of over current relay. The most widely used overload relay is the thermal overload relay where a bimetallic strip is used to turn off the motor. The basic working principle of thermal relay is that when a bimetallic strip is heated up by a heating coil carrying over current of the system it bends and makes normally open contacts. Current flows through the overload relay while the motor is running.

The working principle of the above differs a little from each other. Thermal overload is widely used for motor protection. Are required to construct this protective relay. Thermal motor protection relays contain three bimetal strips together with a trip mechanism in a housing made of insulating material.

In the direct heating method the full current to the motor. In an over current relay there would be essentially a current coil when normal current flows through this coil the magnetic effect generated by the. Working principle of thermal relay a thermal relay works depending upon the above mentioned property of metals. Basically thermal overload relay is an overcurrent protection of the simplest type.

Thermal overload is widely used for. An adjustment dial located on the unit allows the ampere trip setting a manual test button. A thermal overload relay works on the heat produced by the excessive overload current the heat produced by the overload current is utilized to trip the motor circuit. Overload relay working principle thermal overload relay thermal overload relay construction working and application.

Working of bimetallic thermal overload relay. Overload relay in a the following illustration shows a motor circuit with a motor circuit manual starter and an overload relay.