(1) Low voltage circuit breaker of the rated voltage and rated current is not less than the normal operating voltage line and the load current is calculated. Setting current

(2) heat release load should be equal to the rated current is controlled. Instantaneous tripping

(3) electromagnetic release setting current should be greater than the peak current that may occur when the normal work load. For controlling the motor of the circuit breaker, the instantaneous tripping current setting can be selected by pressing the formula: Iz≥KIst where: K is a safety factor, preferably 1.5 ~ L7; Ist starting current of the motor.

(4) undervoltage release nominal voltage shall be equal to the rated voltage of the line. Ultimate breaking capacity

(5) the circuit breaker is not less than the maximum short-circuit current circuit.