Short-circuit maintenance (overload maintenance) is an important function of circuit breakers, and the reason why this function is achieved is that the circuit breaker senses the temperature in the circuit through a thermal iron plate. Once the temperature in the circuit is too high, it is transmitted to the mechanical mechanism in the circuit breaker for trip maintenance.
The key to the selection of a circuit breaker is often its rated current. This is the maximum current at which the circuit breaker circuit is under maintenance. Once this current is exceeded, the circuit breaker will think that the circuit is overloaded or short-circuited and trip. Generally speaking, the commonly used circuit breaker models in the family are C20, C32, and C63.
This choice is crucial. If the selection is too large, the practice current in the circuit will exceed the maximum load of the line, but it will not reach the fault current value of the circuit breaker, resulting in the fault not tripping.
If the selection is too small, it will cause normal use. Do not trip the circuit breaker. Then, when a short circuit occurs in the circuit, the multi-stage circuit breakers trip together – i.e., the branch circuit breaker and the main switch trip together. Is it because you chose the wrong one?
Apparently not. In general selection, the current of the main switch must be greater than that of the branch switch. Then when a short circuit occurs in the circuit, the current in the circuit is huge, and the current value far exceeds the rated current of the branch switch and the main switch. As a result, both switches sense current, so they trip together.
When does just one switch trip? The above is a special case of overloading. In most cases, an overload does not result in an instantaneous increase in current, but rather a cumulative increase in current through different electrical appliances.
At this point, the overload current exceeds the rated current of the branch circuit breaker, but has not yet reached the rated current of the main switch. Therefore, at this moment, as long as the branch circuit breaker will trip.
Skipping tripping means that when the circuit fails, the branch Delixi circuit breaker does not trip, but the main switch trips. This condition is attributed to the wrong circuit breaker selection. If the rated current of the main switch is less than the rated current of the branch switch, the main switch will trip before the branch switch. In this way, the branch switch does not work.
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