Short Circuit Protection Of Incoming Circuit Breaker Of Low Voltage Pole Mounted Distribution Cabinet

Short-circuit protection setting current: Idz=Kk Mgh Ieb
Where: Mgh—overcurrent multiple, determined by the possible peak current, and in non-special cases, determined by the sum of the starting current of the largest motor and other load currents. Mgh is generally 2~10, and should be determined based on the selected Lv Pole Mounted Circuit Breakers samples/
Kk—reliability coefficient, generally 1.2
Sensitivity verification: K=K2
Where: Imin—minimum three-phase short-circuit current at the end of the protected line (A)
K--relative sensitivity coefficient for two-phase short circuit, 0.87
Id2—low-voltage column-mounted circuit breaker short-circuit protection setting current (A)
Note: Sensitivity verification K is generally greater than 2. Sensitivity verification is generally not considered during design.