The difference between electromagnetic and electronic

Update date:2018-03-19 Source:MAXGE

The difference between electromagnetic and electronic

  Molded case circuit breakers are also referred to as device breakers. All parts are sealed in plastic housings. Auxiliary contacts, undervoltage releases, and shunt releases are modular. Because of its very compact structure, molded case circuit breakers cannot be overhauled. Many of them use manual operation, large-capacity optional electric split. Due to the application of electronic over-current release, molded case circuit breakers can also be divided into two types: Class A and B. Class B has good three-stage protection characteristics, but due to price factors, the use of thermal magnetic release Class A products have a higher market share.


  Molded Case Circuit Breakers are equipped with contacts, arc extinguishing chambers, trip units,  and operating mechanisms in a plastic housing. They are generally not considered maintenance and are suitable for use as branch circuit breakers. Over-current trip units have thermal magnets. Both type and electronic type, general thermal magnetic type MCCB is a non-selective type circuit breaker, and there are only two types of protection methods: overload long delay and short-circuit transient. The electronic type MCCB has overload long delay and short circuit. Delay, short-circuit instantaneous and ground fault four protection functions. Some of the new electronic molded case circuit breaker products also feature regional selective chaining. Most molded case circuit breakers are manually operated and some have motor operating mechanisms.


  Molded case circuit breaker thermal electromagnetic type, most of the previous circuit breakers are this structure, that is, the use of electrical thermal effects and electrical magnetic effects, the thermal effect is the use of bimetallic structure to implement, after the switch current is large, the bimetal bending Deformation, deformation to a certain extent, push the tripping device of the switch, trip the switch, adjust the thermal overload current of the switch through the mechanical adjustment screw, the adjustment accuracy is not high, it belongs to inverse time limit action, that is, the greater the current, the shorter the action time. Some large switches such as electric circuit breakers.


  The thermal overload current does not directly adopt the bimetal structure, but uses the current transformer to convert the primary current into the secondary current, and controls the trip coil by accessing the thermal relay through the normally open or normally closed contact of the thermal relay. To make the switch open, instantaneous high-current tripping is to use magnetic effect, there is a structure like electromagnetic coil at the lower end of the switch, when there is a large current or short-circuit current (larger than the overload current of the switch, 0, causing the suction of the electromagnetic coil to increase directly Drive the tripping device and adjust the momentary trip current of the switch by mechanical adjustment screw.


  Thermal electromagnetic structure does not require an external power supply, strong anti-interference. It is possible not to use a trip coil.

  Electronic type is through the current transformer circuit, check the switch current, the current value to control the output, output control the trip coil, so that the switch trip, the advantage is high precision, easy adjustment, directly set the value or use potentiometer adjustment.

The disadvantage is the need to use the trip coil, the need for power, the electronic circuit is more difficult to deal with the problem, the anti-jamming capability is almost.

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