Molded Case Circuit Breaker Troubleshooting

Traditional molded case circuit breakers use electromechanical (thermal-magnetic) trip units that can be fixed or interchangeable. MCCBs provide protection by combining temperature sensitive equipment with current sensitive electromagnetic equipment. Both devices act mechanically on the trip mechanism. In the use of molded case circuit breakers, various faults will be found, and frequent tripping of molded case circuit breakers is one of the common fault phenomena.

Possible causes of MCCBs Tripping

1. Overload: At the same time, the use of too many high-power electrical appliances exceeds the bearing range of the molded case circuit breaker. Once the current trip is set, the molded case circuit breaker will automatically cut off the current, which is often referred to as tripping. In response to this phenomenon, the high-load molded case circuit breaker can be replaced, or the number of electrical appliances can be limited to achieve a stable effect.
2. Short circuit: A short circuit is a circuit failure phenomenon that occurs in power lines and electrical equipment. If in the power supply line, the current does not flow through the power supply, but directly flows from the positive to the negative pole, this situation is called a short circuit phenomenon. run. There are many cases of short circuits. There are three main reasons. The first is that the components on the electrical appliance are damaged, resulting in a short circuit of the power supply. The second is the influence of weather conditions. Long-term rain damage or lightning voltage generated by lightning strikes will cause short-circuits in power lines.
3. Human factors: Such as inadvertent misoperation, which leads to a short circuit of the power supply. You can notify professional maintenance personnel to check the circuit, check whether it is a short circuit, and then deal with it accordingly.

Two ways to solve the tripping of MCCB

1. The processing method for ground fault tripping (ground fault indicator light is on) is to check the breaking current value and operating time of the release. If it is confirmed that there is a ground fault, find and eliminate it immediately. If there is no ground fault, check whether the ground fault current setting value is appropriate. If the setting is not suitable, modify the ground fault current setting value.
2. The general solution for the tripping of the undervoltage release and the mechanical interlocking action is to check whether the power supply is lower than 70% Ue and whether the undervoltage release and the control unit are faulty.

There are many reasons why the molded case circuit breaker cannot be closed after tripping. For example, the undervoltage release can not be closed due to the loss of power, and the voltage is too low or the coil of the undervoltage release is de-energized.