Overload Relay Working Principle Pdf

Thermal motor protection relays contain three bimetal strips together with a trip mechanism in a housing made of insulating material.

Overload relay working principle pdf. 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. Working principle of over current relay. 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. Excess current will cause the overload relay to trip at a predetermined level opening the circuit between the power source and the motor.

Working of bimetallic thermal overload relay. Let us discuss it in the following sections. An adjustment dial located on the unit allows the ampere trip setting a manual test button. 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. The working principle of thermal overload relay is quite simple but interesting. Thermal overload is widely used for motor protection. 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.

Thermal overload is widely used for. Current flows through the overload relay while the motor is running. Overload relay in a the following illustration shows a motor circuit with a motor circuit manual starter and an overload relay. The working principle of the above differs a little from each other.

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. I hope you will find this article informative and helpful. Read more thermal overload.

Are required to construct this protective relay. As explained above a bimetallic thermal relay works on heating property of bimetallic strip. 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. 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. Overload relay working principle thermal overload relay thermal overload relay construction working and application.