1) The selection of circuit breakers must meet the basic requirements of the circuit breaker's own load nature and fault categories;

2) The rated voltage value and frequency of the circuit breaker must be compatible with the nominal voltage and nominal frequency of the circuit in which it is located. In addition, during normal operation, the rated current value of the low-voltage circuit breaker must be greater than the load calculated current value of the circuit in which it is located;

3) When selecting a suitable low-voltage circuit breaker, fully consider the surrounding environmental conditions;

4) Under short-circuit conditions, the low-voltage circuit breaker must be able to meet the basic requirements of dynamic stability and thermal stability. To ensure the normal operation of the low-voltage power distribution system, we must first be able to meet the selective action between the upper and lower stages of the circuit breaker. In actual work, most upper-level circuit breakers will choose to use selective circuit breakers, while lower-level circuit breakers will choose to use non-selective circuit breakers. Such selection can use delay action to obtain selectivity.

Small wiring circuit breakers generally refer to small circuit breakers suitable for AC 50 / 60Hz, rated current to 60A, and rated voltage 230 / 400V. They are mainly used for line overload and short circuit protection. Because of their simplicity and practicality, they are overloaded in the circuit. When it is short circuited, it will automatically cut off the power to protect the circuit, so it is also one of the more common electrical devices. Various places are common, but some situations are not suitable or cannot be used. Talk about the circumstances under which such wiring breakers are not recommended or cannot be used.

First, the circuit breaker is mainly used for overcurrent protection in the circuit. When the circuit is overloaded or short-circuited, the current is too large. When it exceeds the appropriate range of the current, the circuit breaker cuts the circuit to prevent the fault from further expanding. Here is a The key point is overcurrent.