(1) the actual cable through the long-term working current, it must be less than or equal to the permitted load current;

(2) according to the normal operation of the load current, check the network voltage loss: under normal circumstances should not exceed 7%, fault condition shall not exceed 10%;

(3) according to the startup check network voltage loss;

(4) with a minimum short circuit current, short circuit protection device sensitivity should comply with the rules.