Since the motor is required to start when the liquid level is high and stop when the liquid level is low, a float is required to calibrate two liquid levels, high and low. The usual practice is to use two floats, one float is installed at a low liquid level, and the other is installed at a high liquid level.
The working process is as follows:
1. When the water level is below the low level, the float switches -S01 and -S02 are in the off state, and the motor stops;
2. When the water level rises to between the low and high levels, -S01 is closed, -S02 is disconnected, and the motor still does not start;
3. When the water level rises to the high level, -S01 closes, -S02 closes, the contactor-K01 coil is energized and the motor starts to work; at the same time the normally open contacts (13,14) of the contactor-K01 are closed, Form self-locking;
4. When the water level drops again between the low level and the high level, -S01 is closed and -S02 is disconnected, but due to the existence of self-locking, the motor still keeps working;
5. After the water level drops below the low level, -S01 is disconnected, -S02 is disconnected, the contactor-K01 coil is de-energized and released, and the motor stops working;
6. The status of the indicator light is similar to manual start and stop, so I won't repeat it.
The control points of the sewage pump from start and stop:
A reasonable height difference between the high and low liquid levels should be maintained. If it is too large, it may cause poor drainage; if the drop is too small, the motor will frequently start and stop, which will affect the life of the motor.