RCCN WeChat QrCode
Mobile WebSiteThe answer is yes, yes. But what is discussed here is only the case of switching to power frequency operation when the inverter fails. Some production machinery is not allowed to stop during operation, such as the cooling water pump of the central air conditioner and the blower of the boiler. During the frequency conversion operation of these mechanical equipment, once the frequency converter trips due to a fault, it must be able to automatically switch to industrial frequency operation and give an audible and visual alarm at the same time. The main circuit of the switch is shown in the figure. In the figure, KM1 is used to connect the power supply to the power input terminal of the inverter; KM2 is used to connect the output terminal of the inverter to the motor; KM3 is used to connect the industrial frequency power supply to the motor. Because the inverter cannot protect the motor from overload during power frequency operation, the thermal relay FR must be used to protect the power frequency motor. If the motor trips due to a fault of the inverter during variable frequency operation, it needs to be switched to industrial frequency operation. The control circuit should first release the contactors KM1 and KM2 to disconnect the motor from the inverter; after a proper delay, close KM3 so that the motor That is to connect to the power frequency power supply and start the power frequency operation. Contactors KM2 and KM3 are never allowed to be connected at the same time. In addition to using electrical locking between the two, it is best to use mechanical locking at the same time.
The switching between motor frequency conversion operation and industrial frequency operation should be automatic.
