Circuit working principle
Start preparation: press button SB2, contactor KM coil is energized, KM normally open auxiliary contact and main contact are closed, normally open auxiliary contact closure lock KM coil is electrically self-locking, KM main contact is closed as inverter Turn on the main power.
Forward rotation control: press the external switch SA of the STF terminal of the inverter, the STF and SD terminals are connected, which is equivalent to the STF terminal input and input forward rotation control signals. The inverter U, V, W terminals output the forward rotation power supply voltage, and the drive motor is positive. Running. Adjusting the potentiometer R outside the terminal, the inverter output power frequency will change, and the motor speed will also change.
Inverter abnormal protection: If abnormal or fault occurs during the running of the inverter, the internal equivalent closed switch between the B and C terminals of the inverter is disconnected, the KM coil of the contactor is de-energized, the KM main contact is disconnected, and the inverter input is cut off. Power supply to protect the inverter.
Stop control: When the inverter is working normally, the switch SA is disconnected, the STF and SD terminals are disconnected, the inverter stops outputting power, and the motor stops.
