220V Cooling Fan necessary conditions

① Control "220V Cooling Fan" circuit supply voltage, the maximum current can be supplied;
② controlled "220V Cooling Fan" circuit voltage and current;
③ charged circuit requires several groups, what form of contact. The selection of the relay, the general control "220V Cooling Fan" circuit supply voltage can be used as a basis for selection. Should give the relay control circuit to provide enough current, otherwise the relay is unstable.