What is the use of an overload relay?

Overload relays cut off current to the motor when a high-current situation develops due to a ground fault, short circuit, phase failure, or mechanical jamming. They are an inexpensive way of avoiding downtime for repair or replacement of failed motors from excessive current.

What is a contactor relay used for?

A contactor is a special type of relay used for switching an electrical circuit on or off. They are most commonly used with electric motors and lighting applications.

What is the difference between breaker and contactor?

An electronic contactor is a simple switching device, whereas the circuit breaker is a protective system. The primary function of a contactor is controlling the power. A circuit breaker does the protecting. Contactor works under normal situations.

What is the difference between contactor and overload relay?

A contactor joins 2 poles together, without a common circuit between them, while a relay has a common contact that connects to a neutral position. Additionally, contactors are commonly rated for up to 1000V, while relays are usually rated to only 250V.

What is contactor overload relay?

Overload relays protect the motor, motor branch circuit, and motor branch circuit components from excessive heat from the overload condition. Overload relays are part of the motor starter (assembly of contactor plus overload relay). They protect the motor by monitoring the current flowing in the circuit.

How does a contactor and overload work?

Overload relays protect a motor by sensing the current going to the motor. Many of these use small heaters, often bi-metallic elements that bend when warmed by current to the motor. When current is too high for too long, heaters open the relay contacts carrying current to the coil of the contactor.

What is the difference between contactor and relay?

Control Relay: It is a device through which contacts in one circuit are operated by an alteration in conditions in the same circuit or in associated circuits. Contactor: It is a device which is used for repeatedly establishing and interrupting an electric circuit under normal conditions.

What is difference between relay and circuit breaker?

Relays are controlling devices whereas Circuit Breakers are switching devices. A Relay can divert signals between two different electric circuits, whereas circuit breaker can only stop or flow the current in the circuit. A Relay won’t be able to prevent the arc.

Which differentiates an overload relay from a circuit breaker?

What is the difference between an overload relay and a contactcontactor?

Contactors are most often used to switch electric motors on and off-line. An overload relay is used to sense both overload and fault conditions and then assert trip commands to a circuit breaker or other protective device.

What is the purpose of an overload relay?

Hence it is necessary to make the motor fail-safe. Overload relay is one such device that protects a motor from damages caused due to overloads and over-currents. It is used with contactors and can be found in motor control centers and motor starters.

What is a contactor used for in electrical circuits?

A contactor is used to switch circuits on/off many thousands of times; more times that a circuit breaker is designed to operate. Contactors are designed to interrupt load currents on the order of 100’s of amps, but not fault current which can be on the order of 10,000’s of amps.

How do bimetallic thermal overload relays work?

The working of a bimetallic thermal overload relay mainly depends on the bimetallic strip’s heating property. In the straight heating technique, the complete flow of current toward the motor can be supplied using the overload relay which is also called OLR.