What are the selection principles of general low-voltage circuit breakers

1) The type and protection form of the circuit breaker shall be determined according to the requirements of the line for protection - frame type, device type or current limiting type shall be selected< Br>2) The rated voltage UN of the circuit breaker shall be equal to or greater than the rated voltage of the protected circuit< Br>3) The rated voltage of the circuit breaker undervoltage release shall be equal to the rated voltage of the protected circuit< Br>4) The rated current of the circuit breaker and the rated current of the over-current release shall be greater than or equal to the calculated current of the protected line< Br>5) The limiting breaking capacity of the circuit breaker shall be greater than the effective value of the maximum short-circuit current of the line< Br>6) The protection characteristics of the upper and lower level circuit breakers in the distribution line should be coordinated, and the protection characteristics of the lower level should be below the protection characteristics of the upper level and not intersect< Br>7) The long time delay tripping current of the circuit breaker shall be less than the continuous current allowed by the conductor< br>