The system constructed here consists of following main circuit components and parts.

1. The sensors, which sense the water levels in the well and the tank.

2. The voltage regulator that monitors the variation of the voltage.

3. The main circuit to control the system.

4. The digital display.

5. The buzzer.

6. The optional switch.

The circuit is designed to operate as follows.

When the water level of the tank is lower than the sensor that is closer to the bottom of the tank. The motor is turned ON through the relay. This continues even after the lower sensor goes under water. When both sensors are in contact with water, Then the motor is turned OFF through the relay stopping the pumping.

When water is used, the water level eventually drops below the upper sensor. However, won’t turn on the power to the motor again. In order to turn on the motor both sensors should not contact with water. Therefore the pumping will start only after the water level drops below the lower sensor. This logic is illustrated in the Table 1.

Table 1: Conditions to turn on and off the motor depending on the signals from the sensors in the tank.

As can be seen above (Table 1), the motor turns on when both sensors upper from water and turn off when both sensors contact with water. After the motor is turned on, it keeps on the upper sensor contact with water, respectively and for the same combination motor is maintained at off state after the motor is turned off. In order to perform this function the previous conditions should be stored.

During the pumping of water the water level in the well drops. In the event the water level is dropping below the upper censer, the motor would not turn off even though the upper censer does not contact with water. However, the motor will turn off automatically if both sensors does not contact with water, which could happen only when the water level is below the lower censer in the well. This condition guarantees that the pumping continues only if the water level is above the put valve. If this happens during the pumping the motor will start again when both sensors contact with water. i.e., after the water level is above the upper sensor in the well. This logic is illustrated in the Table 2.

Table 2: Conditions to turn on and off the motor depending on the signals from the sensors in the well.

The buzzer is to indicate the low water level of the well. if the water level is below the lower sensor which is just above the put valve, then motor is turned off and the buzzer is turned on and the indicating that the motor turned off due to low water level in the well.

The motor is OFF when the tank is filled up to the higher level and it starts again when it goes pass the lower level of sensor. A digital display is constructed to indicate the water level of the tank. four different water sensors are used to determine the water level of the tank. depending on the water level in the tank the display will indicate one of the five regions in the tank depending on the height. This will be displayed by a digit in the display from 0 to 4 with 4 indicating the highest level.

The voltage regulator unit monitors the fluctuations of the supply voltage. When the supply voltage reaches a set value above which the motor and the component of the circuit could damage, the unit automatically cut off the main supply to the main circuit and the motor. This will protect the motor and the other component of the system from damages due to high voltages. when the supply voltage is in the range between 200V to 250V AC the regulator provides a constant 12V DC to all circuits. The relay is turned on only if the supplied voltage is within the above range for the protection of instruments. The range can be adjusted manually if needed. If the supply voltage were out of the selected range the power would not supply to the circuit. When the power is back to the safe range again the circuit will turn on with a delay of 2¹/₂ minutes. Similarly, the regulator will deliver power to the circuit with the same delay after a power failure, if any, in the house hold power supply. Hence the motor will be safe for unexpected power fluctuations. The level of the voltage, whether the voltage is higher, lower or at the relevant voltage level, is displayed using state indicator LED. The red LED in higher voltages, yellow in lower voltages and green one in relevant value and blinking green during the delay time. That would indicate the quality of the power supply and whether the relay is ON or OFF.

In case if one wants to fill the tank before the water level drops below the lower sensor in the tank then one could use the push button switch. This will turn on the motor regardless of the water level in the tank. The motor will stop when the tank is full up to the upper sensor. For example, if the water level is just above the lower sensor and one wants to make sure that the tank has sufficient water to take a bath in order to avoid the situation of not having water during the bath due to a power failure, then the push button switch can be used to fill the tank.

Water Sensor for well

Water Sensor for Tank

Voltage Regulator Unit

Main Circuit

Digital Display