Irrigation motor automatic protection circuit

How the circuit works: When irrigating, press the double throw button switch AN z. , AN2b,
transformer T is energized, prompting the second set of contacts Kz to jump up, replacing AN2a, AN u,
thus making the three-phase relay controlling the motor work. When the voltage is low, if a certain phase
fuse burns out, the bulbs connected in parallel at both ends of the fuse box will light up. The infrared receiving tube will
quickly conduct after receiving the light, prompting the transistor 3DG12 to work, giving K. Provide loop
current, quickly change from normally closed to open, cut off the power supply of Kz, the two sets of contacts of Kz
pop open, thereby cutting off the power supply of the three-phase relay, and shut down the motor .