Here we need to see how to solve the problem if we are using the stripper of low-voltage molded case circuit breaker, because the stripper of molded case circuit breaker is divided into instantaneous trip and overload trip. In the instantaneous and overload trip, they are collectively called compound trip and do not include shunt trip. In addition, the instantaneous and overload trip are in the The inner part of the molded case circuit breaker is usually attached to the molded case circuit breaker paper, so the shunt release is also the release of the electric break circuit breaker and uses the external power supply to provide the power supply for tripping, which is mainly used for remote breaking of the circuit breaker.
And the instantaneous trip is short-circuit trip and is generally five to ten times and ten to fifteen times of rated current trip. This overload trip is generally under one point three times of rated current without trip within one hour and under one point four five times of rated current within one hour, which is the standard for shorts under the condition of constant temperature of 40 degrees 。
In motor distribution, the instantaneous release with rated current of 10-15 times is generally selected and the molded case circuit breaker with rated current of 5-10 times is generally selected for distribution. The shunt release mainly depends on whether it needs remote operation. We also need to see whether the remote closed circuit breaker needs to be equipped with electric operator.
If it is the fault analysis, judgment and treatment of the circuit breaker's false tripping during operation, if we have no short circuit and no direct grounding phenomenon in the system, and the relay protection has no action, then the molded case circuit breaker will trip automatically, so it is called the circuit breaker as false tripping, but the analysis of the false tripping still has judgment and treatment generally, we need to divide it into the following three steps Conduct.
We need to judge that the ammeter and signal indicator light are normal before tripping and indicate that there is no short circuit fault in the system. Another is that the green light flashes continuously after tripping and the red light goes out. If this happens, the ammeter of the circuit breaker will not only display the active and reactive power as above zero, then we can judge it as false tripping. If we confirm that We need to deal with the reasons separately.
If the false tripping is caused by personnel's wrong touch or wrong operation and may be caused by mechanical external force vibration and the protection disk is caused by external force vibration, we should eliminate the cause of switch ancient equipment and immediately power on. If this is not useful, it may be part of other electrical or mechanical faults Then we need to contact the maintenance personnel immediately and stop the trip breaker.
If we check and analyze the electrical and mechanical faults of the false tripping circuit breaker, the first reason is that the electrical faults are caused by the protection maloperation or improper positioning, or the current and voltage transformer circuit fault, or the secondary circuit insulation adverse reaction, or the DC system two-point grounding It is possible that the mechanical fault is caused by the tripping caused by the closing maintenance bracket and the opening lock.