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Auto & Manual Control of 1-Phase Water Pump Motor using Float Switch

Automatic and Manual Control of Single Phase Water Pump Motor using Float Switch

Water motors are widely used in various applications such as pumping water from wells, tanks, and reservoirs. They are essential for irrigation systems, domestic water supply, and industrial processes. Controlling the operation of a water motor efficiently is crucial to ensure optimal performance and prevent wastage of resources. One common method of controlling a water pump motor is by using a float switch, which can be operated manually or automatically. In this article, we will explore the automatic and manual control of a single-phase water motor using a float switch with power and control wiring diagrams.

Overview of a Float Switch

A float switch is a simple yet effective device used to control the level of liquid in a tank or reservoir. It consists of a buoyant float attached to an electrical switch. The switch is actuated by the movement of the float as the liquid level rises or falls. When the liquid level reaches a certain threshold, the float rises or falls, triggering the switch to turn the motor on or off.

Components Required

  • Water Pump Motor – 1-Phase
  • MCB – 63A, 2-P
  • RCD – 40-50A – 2P
  • Contactor
  • Thermal Overload Relay
  • ON/OFF Selector Switch
  • Float Switch
  • 230V Single-Phase AC Supply
  • Wires and Cables and additionally (indicators & ON OFF switches if needed)

Wiring & Control Diagram

The following wiring and control diagram demonstrates how to control a 230V single-phase water pump motor using a float switch for both automatic and manual operations.

Click image to enlarge

Automatic & Manual Control of 1-Phase Water Pump Motor Using Float Switch

Working & Operation

Manual Control using Float Switch

In manual mode, the float switch is directly connected to the water motor. The switch (when the the ON/OFF selector switch knob is on the Manual Operation) is equipped with two positions: “ON” and “OFF.” When the float is in the “ON” position, it indicates that the water level has dropped below the desired level.

As a result, the motor is activated, and water is pumped into the tank or reservoir. When the float reaches the “OFF” position, it indicates that the water level has risen to the desired level, and the motor is switched off.

Manual control using a float switch provides a simple and reliable method for operating a water motor. It allows users to manually regulate the water level based on their requirements. However, it requires constant monitoring to ensure that the motor is turned on or off at the appropriate times.

Automatic Control using Float Switch:

To achieve automatic control, additional components such as a contactor, relay and a control circuit are integrated into the system. The float switch is connected to the control circuit using ON/OFF selector switch, which acts as an intermediary between the float switch and the motor.

When the knob is on the Automatic Position, the control circuit interprets the signals from the float switch and controls the operation of the motor accordingly.

In automatic mode, when the water level falls below the desired level, the float switch triggers the control circuit, which activates the motor. The control circuit energizes the relay, allowing power to flow to the motor.

As a result, the motor starts pumping water until the float switch indicates that the desired water level has been reached. At this point, the control circuit deactivates the relay, cutting off the power supply to the motor and stopping the pumping process.

Automatic control offers several advantages over manual control. It eliminates the need for constant monitoring, allowing the system to operate independently. It ensures that the water motor operates only when necessary, preventing unnecessary power consumption and wear on the motor. Additionally, automatic control enhances safety by reducing the risk of overflows or dry-running of the motor.

Choosing Between Manual and Automatic Control

The choice between manual and automatic control depends on various factors such as the application, user preferences, and available resources. Manual control is suitable for situations where the water level needs to be adjusted frequently or when immediate control is desired. It is simpler, less expensive, and requires minimal setup.

On the other hand, automatic control is beneficial when continuous operation and precise water level management are required. It offers convenience, energy efficiency, and improved system reliability.


Controlling a single-phase water motor using a float switch provides an effective means of regulating water levels in tanks or reservoirs. Whether employing manual or automatic control, the float switch plays a vital role in activating or deactivating the motor based on the desired water level. Manual control offers simplicity and affordability, while automatic control offers convenience.

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