Universal circuit breaker common causes of failure and handling methods

Miniature Circuit breaker (MCB) is a switching device that can close, carry and open the current under normal circuit conditions and can close, carry and open the current under abnormal circuit conditions within a specified period of time. The circuit breaker can be used to distribute electrical energy, start asynchronous motors infrequently, protect power lines and motors, etc., and automatically cut off the circuit when they are seriously overloaded or short-circuited and under-voltage faults occur, and its function is equivalent to the combination of fuse-type switch and over-under thermal relay. And after breaking the fault current generally do not need to change the parts. At present, has been widely used. Circuit breaker according to its use is divided into high-voltage circuit breakers, and low-voltage circuit breakers, high-voltage boundary division is relatively vague, generally more than 3kV called high-voltage appliances.

Universal circuit breakers are also often called frame circuit breakers because they are wrapped in a layer of frame on the outside, and this statement is still very common. Universal circuit breakers in the process of use sometimes occur in the main contacts do not close or during the closure and then disconnect themselves, thus causing some unnecessary damage. Study its causes, there may be the following points.

(1) Due to the release of energy coil often through the high current, resulting in coil overheating, causing unstable work. 

(2) Due to the relay being under high voltage for a long time, causing the contact surface to oxidize and the contact resistance to become large, the contact cannot be connected to work properly.

(3) Due to the stator and rotor in the motor misalignment, friction with each other, generating a lot of heat, causing the motor speed instability, or even stall, resulting in the universal circuit breaker can not work properly.

Common fault handling methods, there are the following.

1. Noise of the undervoltage detriggers

Undervoltage decoupler work for a period of time often produces abnormal noise, lightly disturbed into, heavy burn coil, so to regularly remove the core working surface of the oil and dust, found short-circuit ring fracture to replace. Also should adjust the spring tension of the under-voltage decoupler, until the core and armature air gap meet the requirements.

2. Burning of micro motor

Faulty travel switch can cause the micro motor in the electric operating mechanism to be burned. For example, when the circuit breaker needs to be closed with the electric operating mechanism, press the close button, the power supply circuit of the motor is connected and the motor rotates, after completing the storage of energy or closing of the mechanism, the power supply circuit of the micro motor should be disconnected by the travel switch, but due to the fault of the travel switch, it cannot be disconnected, which will make the motor overheat and burn up after long operation.

3. Short circuit caused by poor insulation

Miniature Circuit breaker by long-term use of insulation performance will gradually deteriorate, if the usual maintenance is not appropriate, insulation parts surface dust accumulation, moisture erosion, will accelerate the aging of insulation, may be in the power distribution operation or cut off the short-circuit current caused by inter-phase or relative to the ground short circuit. So keep the insulation surface clean, to prevent the insulation performance deterioration, in order to extend the service life of the circuit breaker.