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What is a molded case circuit breaker: Molded case circuit breakers, also known as device circuit breakers, each component is sealed in a plastic case, and the auxiliary contacts, undervoltage releases and their encouraged releases are mainly modularized.

Molded case circuit breakers are basically impossible to repair due to their very compact structure. It is mainly operated manually, and electric division can be selected for large spaces. Due to the application of electronic overcurrent release, molded case circuit breakers can also be divided into A and B types. B type has good three-level maintenance characteristics, but due to price factors, the A type of thermal magnetic release is selected. Market share is high. Molded case circuit breaker is a contact. Arc interrupter.

The release and operating mechanism are installed in the plastic case. Generally, maintenance is not considered. It is suitable for environmental protection switches. The circuit breaker is a non-selective circuit breaker, with only two protection modes: long load delay and short circuit instantaneous. The electronic case circuit breaker has four maintenance functions: load long delay, short circuit short delay, short circuit instantaneous and ground fault. Some new electronic molded case circuit breakers also have a regional selective interlocking function. Most molded case circuit breakers are manually operated, and there are also some operating mechanisms with motors.

The working principle of the molded case circuit breaker: Molded case circuit breakers are those that automatically disconnect the current after the current exceeds the setting. Plastic case refers to a case with plastic insulation as a device type, which is used to protect the metal parts between conductors and grounding. Molded case circuit breakers generally contain a thermomagnetic removal module, while larger molded case circuit breakers will be equipped with solid removal sensors. The trip module is divided into: thermal magnetic trip and electronic trip. Generally speaking, it is composed of contact system, arc extinguishing system, operating mechanism, release device, shell and so on. When a short circuit occurs, the magnetic field generated by the large current (usually 10 to 12 times) overcomes the shaft torsion spring, the release drives the operating mechanism to move, and the switch trips instantaneously. When loaded, the current increases, the calorific value increases, and the bimetallic sheet deforms to promote tissue movement to a certain extent (the more current, the less movement time). Now there are electronic types, which use the transformer to collect the current size of each phase, compared with the preset value, when the current is abnormal, the microcontroller sends a signal to make the electronic release push the action of the operating mechanism.

The function of the circuit breaker is to disconnect and connect the load circuit, and disconnect the fault circuit to prevent the accident from expanding and ensure safe operation. The high-voltage circuit breaker should disconnect 15,000 V units, and the current should be 1500-2000A electric arcs. These electric arcs can be extended to 2m and continue to burn without going out. Therefore, arc extinguishing is a problem that high-voltage circuit breakers must solve. The principle of arc blowing and arc extinguishing is mainly the weak heat dispersion of the refrigeration electricity. On the other hand, according to the arc blowing, the electric isolation is elongated, the composite diffusion of the charged particles is strengthened, and the charged particles are floated in the arc gap at the same time, and the dielectric strength of the medium is quickly repaired. The difference between molded case circuit breakers and miniature circuit breakers: Molded case circuit breakers are mainly used for loads in low-voltage power distribution systems and motor protection circuits. Short circuit provides protection. Due to its reliability and stability, it has become a widely used product in industry.