15 April 2021

Difference Between relay and Circuit Breaker

Understand the distinction between a relay and a circuit breaker. Definition, use, power, capacity, voltage input, amplification, contact breaking, and arc prevention are some of the comparison criteria. So here this article gives information about the key difference between relay and circuit breaker to better understand this topic.

What is Relay?

Realy act as switches in a circuit involving small currents. The relay consists of electromagnets, which become energized when current flows around them. When the current becomes large enough, the electromagnet is able to pull one of the contact in a circuit towards itself, breaking the circuit.

What is a circuit breaker?

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current, typically resulting from an overload or short circuit. A circuit breaker consists of fixed and moving contacts known as electrodes.

Difference between the relay and circuit breaker:

  • The relay does not break the contact. It only senses the error and sends the signal to the circuit breaker whereas the circuit breaker breaks the circuit contacts
  • The relay is a switching and sensing device, while the circuit breaker is an isolating or disconnecting device.
  • Relay acts as an electrical amplifier for discrete signals, while the circuit breaker does not act as an amplifier.
  • The relay is used to control or select one among many circuits, while the circuit breaker is one per circuit.
  • The relay operates on low power input voltage, The circuit breaker is automatic on the load device
  • Relay can be directional and non-directional, while the circuit breaker is nondirectional only.
  • A relay is a switching device that gives a signal to the circuit breaker as soon as the fault occurs in the power system, while the circuit breaker breaks the circuit automatically when receives the signals from the relay.
  • A relay may be included in a circuit breaker, but a circuit breaker is not included in the relay
  • A relay won't be able to prevent the arc, there may be a mechanism to detect the formation of the arc and prevent it. 
  • Relay is controlling devices while the circuit breaker is switching devices.
  • Relay is a switch acting as a sensing device while the circuit breaker is used for disconnect and isolation of the circuit.
  • Relay can be diverted signal between two different electric circuits, whereas circuit breakers can only stop or flow the current in the circuit.
  • Relay can be used as an amplifier in case of discrete signals, it converts one signal to many amplify a low voltage signal into a high voltage signal and vice versa. The circuit breaker can't be used as an amplifier.
  • SPST, SPDT, DPST, DPDT, EMR, SSR, electromechanical, REED, and hybrid relay are the example of Relay, while the MCB, VCB, SF6 are the example of the circuit breaker.
Explore more information: