Molded case circuit breaker refers to the ability to automatically cut off the current after the current exceeds the trip setting. Plastic case refers to the use of plastic insulators as the housing of the device to isolate between conductors and ground metal parts. Molded case circuit breakers usually contain a thermal magnetic trip unit, while large models of molded case circuit breakers are equipped with solid state trip sensors. The trip unit is divided into: thermal magnetic trip and electronic trip.
Circuit breakers are generally composed of contact systems, arc extinguishing systems, operating mechanisms, trip units, and housings.
When a short circuit occurs, the magnetic field generated by a large current generally 10 to 12 times overcomes the reaction force spring, the tripper pulls the operating mechanism, and the switch momentarily trips. When the overload occurs, the current becomes larger, the heat generation is intensified, and the deformation of the bimetal sheet to a certain extent drives the mechanism to operate with a larger current and a shorter operation time.
There are electronic types, which use transformers to collect the current of each phase and compare it with the set value. When the current is abnormal, the microprocessor sends a signal to cause the electronic release to drive the operating mechanism.
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Working principle of molded case circuit breaker
2019-12-23 09:21:57 9401 Clicks