Relay
is a protective device which senses the faulty conditions in a power system line and initiates
the operation of circuit breaker to isolate the faulty part from the rest of
the healthy power system. That means a relay senses a
condition (voltage, flow, amperage, pressure, level, etc.) and allows component
actuations (circuit breaker operation, pump start, valve open/close etc.) to
occur Examples of relays are Over Current
relay, Directional relay, etc.
A
circuit breaker is a device for the limiting of current
supplied to a circuit. Circuit Breaker is a device which can
- Make
or break circuit under normal conditions either manually or through remote
control.
- Break
circuit automatically under faulty conditions.
- Make
or break circuit under faulty conditions either manually or through remote
control.
Some
types of circuit breakers are Air blast circuit breakers, Vaccum Circuit Breakers,
SF6 Circuit Breakers etc. You can notice the circuit breakers near to the
transformers. Next time, when you will see a transformer search for the circuit
breaker. Mostly it will be SF6 Circuit Breakers.
What is the difference between Relay and Circuit Breaker?
• The relay is used for controlling a circuit with isolation between control
circuit and the controlled circuit. Circuit breaker is used for disconnecting
or isolating a circuit from the power source or a higher level circuit.
• The relay operates on a low power voltage input while circuit breakers are
automatic on-load devices.
• Circuit breakers are used one per circuit while relays can be used to
control/select one among many connected to it.
• A relay may be included in a circuit breaker, but not the other way
around.
• A relay can also be considered as an electrical amplifier for discrete
signals.
