The principle of selecting the parameters of commonly used circuit breakers

(1) General selection principles
Select the type and number of poles of the circuit breaker according to the application, select the rated current of the circuit breaker according to the maximum working current, select the type of tripper, the type and specification of the accessories according to the need.
The specific requirements are:
1) The rated working voltage of the circuit breaker ≥ the rated voltage of the line;
2) The rated short-circuit on-off capacity of the circuit breaker ≥ calculate the load current of the line;
3) The rated short-circuit on-off capacity of the circuit breaker ≥ the maximum short-circuit current that may occur in the line (generally calculated according to the effective value);
4) The single-to-ground short-circuit current at the end of the line ≥ 1.25 times the instantaneous (or short-delay) tripping setting current of the circuit breaker;
5) The rated voltage of the undervoltage tripper of the circuit breaker is equal to the rated voltage of the line;
6) The rated voltage of the shunt tripper of the circuit breaker is equal to the control power supply voltage;
7) The rated working voltage of the electric transmission mechanism is equal to the control power supply voltage;
8) When the circuit breaker is used in the lighting circuit, the instantaneous setting current of the electromagnetic tripper is generally 6 times of the load current.