Automatic switching circuit for motor Y-△ connection

Working principle of the circuit: In the figure, VD, C, Crown, R2, RP, and ￡ form a signal sampling
circuit. The main circuit current of the motor is sensed to terminals n and 6 through the transformer ￡, and
the DC voltage is rectified by VD and filtered by C. Add to R. , both ends of R2 are divided and sent to the comparator
for comparison, and the output signal is sent to VT for amplification to drive JZ. The sampling signal is proportional to the current of the main circuit of the motor . Adjusting RP, and RP2 can determine the main circuit . The electrical signal obtained by the secondary side of ￡ must be above tens of millivolts, that is, it must be greater than the minimum voltage required by the comparator.