Power switch integrated water level automatic control circuit

The figure shows an automatic water level control circuit composed of a power switch integrated circuit TWH8751. When the water level is below the detection poles B and C, pin ② of the IC is low level, and pin 4 outputs low level, relay K is energized, 5 and 6 of K are closed, and the light-emitting diode H lights up, indicating that it is working; 3 and 4 of the normally closed contact K are disconnected, 1 and 2 of the normally open contact K are closed, the AC contactor KM is electrically closed, the water pump motor M is running, and water is injected into the pool. The water level rises to electrode A, the ② pin of IC changes from low level to high level (>1.5V), the ④ pin of IC is high level, K loses power and is released, K contacts 5 and 6 are disconnected, and the light Off; contacts 1 and 2 of K are disconnected, KM is released due to loss of power, motor M is powered off, and pumping stops. When the water level in the pool drops and leaves point A, since 3 and 4 of K are normally closed contacts, IC pins ② and ④ still maintain high level, and motor M is still in a stopped state. The pumping equipment will only work when the water level in the pool is lower than point B. S1 is the power switch of the control circuit. S2 is the manual switch of the water pump motor M. When it is closed, the KM will run to pump water, and when it is closed, the pump will stop.