Water tower automatic water supply circuit

When the water source is sufficient, the water in the water tower is kept stable; when the water source is insufficient, the water pump stops pumping to avoid empty pumping. The circuit is simple and
easy to make and debug.
    The electrical schematic of the device is shown in the figure. When the water level in the water tower is above point A, the resistance between A and C is small, VT3 is saturated and conducts, and K
is attracted. KM is released, and the water pump motor is powered off; the water pump does not pump water, and the normally closed contact KM of the contactor is closed; when the water level in the water tower drops
below point A and above point B, because KM is closed, VT3 is maintained on, and the water pump still does not pump water. }When the water level in the water tower drops below point C
, there are large resistances between A and B and between B and C, VT3 is cut off, K is released, the normally closed contact K of the relay is closed, KM is muted, and the water pump
pumps water . At the same time, KM is disconnected; the water level in the water tower gradually rises. When it reaches point B, VT3 is still cut off because KM is disconnected, and the water pump continues to pump water
. When the water level rises to point A, the situation is the same as before, and the water pump stops pumping water.
    When the water level in the well is above point A, or when the water pump pumps water (KM is closed), it is above point B, the resistance between Shu and the ground is small, VT1
is saturated, and VT2 is cut off. There is no impact on the operation of VT3. But when the water level in the water is lower than point C, the resistance to ground is very large, VT1 is cut off,
the collector of VTI is high level, VT2 is turned on, causing VT3 to be turned on, forcing the water pump to stop. Because KM is disconnected, only when the water level in the well rises
above point A, VT1 is saturated, and the permanent pump can work according to the water level in the water tower.