Power Inverter "220V Cooling Fan" bad - take ACS800,690V drive, for example, rectifier unit and the inverter unit fan is broken, will be reported drive overtemperature protection --- inspection methods, measuring fan is Not really bad, if true replace it; if it is not broke, check the control loops and micro-switch is normal; a common fault is - drive fan panel is damaged, resulting in "220V Cooling Fan" does not turn, resolve Measures can be considered as directly connected to the external power supply fan power supply; if micro switch is bad, for one, or emergency when short micro switch that; after taking these measures to prevent overheating when the drive is actually normal alarm, You can take a temperature sensor, temperature switch contacts connected to the control circuit to go, after overtemperature - can jump stop, protect the drive; if this series inverter rectifier unit and the inverter unit "220V Cooling Fan" is not turn, check the DC bus circuit to take power after the initial source of the fan power is DC bus; this series Roof fan does not turn, check the auxiliary power supply control loop;