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Circuit breaker

A circuit breaker is a electrical protective device which protects electric load devices and an electric power cable from a large accident current caused by an electrical shortage and a ground fault which may be generated on an electric circuit, and it performs a breaking operation automatically when such an accident current is generated, whereby the circuit is broken. In many applications, a circuit breaker may provide ground fault protection. Typically, an electronic circuit detects leakage of current to ground and generates a ground fault trip signal. This trip signal energizes a shunt trip solenoid, which unlatches the operating mechanism, typically through actuation of the thermal-magnetic trip device. Typically, circuit breakers include a spring-powered operating mechanism which opens electrical contacts to interrupt the current through the conductors in an electrical system in response to abnormal conditions. Circuit breakers may include an electronic trip unit that senses electrical current to the protected equipment. If the sensed electrical current indicates an overcurrent situation, the electronic trip unit provides a trip signal to a trip actuator. In response to the trip signal, the trip actuator actuates a mechanical operating mechanism. Actuation of the mechanical operating mechanism by the trip actuator causes the mechanical operating mechanism to separate the electrical contacts, stopping the flow of current to the protected equipment. Circuit breakers are rated by voltage, insulation level, current interrupting capabilities, transient recovery voltage, interruption time, and trip delay. The medium in which circuit interruption is performed may be designated by a suitable prefix, for example, air-blast circuit breaker, gas circuit breaker, oil circuit breaker, or vacuum circuit breaker. A vacuum circuit breaker connects or interrupts current between a power source and a load of high voltage and current, for example, over thousands of voltages and of hundreds amperes. Vacuum circuit breakers each contain an electrode structure composed of a pair of a fixed electrode and a movable electrode. Air circuit breakers are commonly used in electrical distribution systems. A typical air circuit breaker comprises a component for connecting an electrical power source to electrical power consumer called a load. The component is referred to as a main contact assembly. Circuit breakers used in residential and light commercial applications are commonly referred to as miniature circuit breakers because of their limited size. In miniature circuit breakers, electrical protection is typically provided by a thermal-magnetic trip device. This trip device includes a bimetal, which heats and bends in response to a persistent overcurrent condition. The bimetal, in turn, unlatches a spring powered operating mechanism, which opens the separable contacts of the circuit breaker to interrupt current flow in the protected power system.

categoryCircuit breaker categories


Air circuit breaker Air circuit breaker (1)

Gas circuit breaker Gas circuit breaker (0)

Miniature circuit breaker Miniature circuit breaker (1)

Vacuum circuit breaker Vacuum circuit breaker (3)




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