Simple overall wiring for self-locking control of motor operation and fault analysis

Physical wiring diagram

Circuit diagram

Working Principle and Fault Analysis:

1. Close QF1 and QF2 to conduct the power supply. Press the jog button SB2. The AC contactor KM coil gets electricity. The main contact closes and the auxiliary contact closes to conduct the power supply. The KM self-locking three-phase asynchronous motor starts to run.

2. Release the SB1 button. The AC contactor coil loses electricity. The main contact resets and disconnects the power supply. The three-phase asynchronous motor stops running.

3. Fault analysis: If the AC contactor does not pull in when the SB2 button is pressed, first check whether the power supply of QF2 is normal (if the voltage is abnormal, the cause of the power supply needs to be found). Use a multimeter to measure whether the voltage is 220V. If the voltage is normal, check the normally closed point of the SB1 button. Press SB2 to see if the normally open point is closed. (If the SB1 and SB2 buttons are not closed, they need to be replaced). If it is normal, check the AC contactor KM coil and use a multimeter to measure whether there is resistance. (If there is no resistance during the measurement, it indicates that the AC contactor coil is damaged and the AC contactor needs to be replaced).

4. If the AC contactor pulls in but the motor does not run, it is necessary to check whether the power supply of QF1 is normal. (If the voltage is abnormal, the cause of the power supply needs to be found). If the power supply of QF1 is normal, check whether the main contacts L1 -T1, L2-T2, and L3-T3 of the AC contactor are conducting. (If any one of the main contacts does not conduct in the closed state, it indicates that the main contact of the AC contactor is broken and needs to be replaced.)

5. If the AC contactor acts but does not self-lock when the SB2 button is pressed, check the self-locking wire. If there is no problem with the self-locking wire, check whether the auxiliary contact 13N0-14N0 conducts when the main contact is closed.