Contactors and circuit breakers are widely used in electrical systems. There are lots of technical differences between them. Let’s compare these two devices.
Differences between contactor and circuit breaker
Contactor and circuit breaker are different devices. There are lots of differences between these products. Some of them are:
Definitions and duties are totally different
A contactor is also a type of switching device that is used for controlling heavy loads like motors, lighting, and heating equipment. A circuit breaker is a protection device that protects circuits against overloads and short circuits.
The contactor must control electrical loads but the circuit breaker must protect electrical loads. The contactor works under normal conditions but the circuit breaker works under abnormal conditions.
The working principle of contactor and circuit breaker is unique
The operating principle of contactor and circuit breaker is completely different.
The working principle of a contactor can be described as follows: When control power flows through the magnet coil of a contactor, the resulting magnetic field attracts the mechanical contact carrier. By interruption of the coil control circuit, the mechanical contact carrier returns to the starting position.
A circuit breaker is a switch that has a piece of metal inside. If the current in the circuit is too high, the metal warms up and bends. When the metal bends, it flips the switch and opens the circuit. The flow of current stops before the wires get too hot.
Applications and usage in a circuit can differ
Contactors are mainly used for controlling 3-phase motors and generally for controlling power circuits. The contactors can also be used for many other applications such as bypass, capacitor switching, lighting, d.c. power circuits. (downstream circuits)
Circuit breakers can be used where circuit protection is needed. (upstream and downstream circuits)
The size of a contactor is larger than MCB; but smaller than MCCB
Generally, the size of a power contactor is larger than a miniature circuit breaker but smaller than molded case circuit breaker and air circuit breaker.
The current carrying capacity of a circuit breaker is higher
The current rating of a contactor is up to around 2000A. The circuit breaker is up to 6300A.
Types of contactor and circuit breaker vary
Contactors have various types such as power, mini, modular, bar-type, capacitor-type. Miniature circuit breakers, molded case circuit breakers, and air circuit breakers are the types of circuit breakers.
The number of the poles can be different
Contactors are available in two-pole, three-pole, and four-pole configurations. 1, 2, 3, and 4 pole circuit breakers are available in the electrical market.
The price of a contactor is cheap but the market size is small
The price of a contactor is cheaper than a circuit breaker but the market size of the circuit breaker is larger than a contactor. You will 100% see a circuit breaker when you open the door of any electrical panel. But you can see contactors in special applications.
Contactor has a longer lifespan
The lifespan of the contactor is longer than circuit breakers. The average lifetime of a C.B is around 10000 but the average lifetime of a contactor goes up to 1000000.
Remote operation is possible with a contactor
Contactors can operate remotely. Remote operation is the basic principle of the contactor. Circuit breakers are also able to operate remotely but an accessory like shunt release, closing release, undervoltage release, or motor operator should be mounted on them.
Manual operation is possible with a circuit breaker
The circuit breaker can be operated manually using its handle. So, a circuit breaker acts as a switch also. You cannot control a contactor manually.
Maintenance of breakers should be done periodically
Contactors do not require much maintenance. However, in the case of permanent heavy load switching, spare parts are offered by manufacturers. Maintenance of circuit breakers should be done periodically.
History and inventor of contactor and circuit breaker are different
The circuit breaker has a longer history compared to the contactor.
An early form of circuit breaker was described by Thomas Edison in an 1879 patent application. Edison’s purpose was to protect lighting circuit wiring from short circuits and overloads. A modern miniature circuit breaker was patented by Brown, Boveri & Cie in 1924. Hugo Stotz.
Hein Moeller developed the first small oil contactor.