Proximity Sensor Connection with Contactor, Relay, and Motor

Hi, in this article, we are going to see the Proximity Sensor Connection Diagram with Contactor, Relay, and Motor. Proximity sensors are used in combination with contactors, relays, and motors in various industrial and automation applications to detect the presence or absence of an object, and then to control the operation of electrical equipment based on this detection. For example, in domestic applications, Proximity Sensors can be used to detect the approach of an object or person, controlling the motor to open or close the door. Similarly, in industrial applications, Proximity sensors can be used to detect objects on the conveyor, controlling the motor driving the belt to start or stop based on the presence of objects.

Connection Diagram

Here, in the below wiring diagram, you can see the connection between Proximity Sensor, Contactor, Relay, and three-phase motor.

Components Used

1. Proximity Sensor: It is used to Detect the presence of an object.
2. 24V Relay: It is an electromagnetic switch used to control the contactor coil and it is operated by the proximity sensor.
3. Contactor: Switches the three-phase power supply to the motor for on and off.
4. Overload Relay: Protects the motor from overload.
5. Motor: The load being driven by the system.
6. Three-Phase MCCB: Provides overcurrent protection for the motor.
7. Single Pole MCB: Provides overcurrent protection for the control circuit.
8. Power Supplies: Here, a 440V three-phase supply is used to drive the motor, a single-phase 230V supply is used for the control circuit means to operate the contactor coil, and the 24V DC supply is used to control the 24V relay coil through the proximity sensor

Wiring Description

1. The three-phase power supply is connected to the three-phase motor through the 3-pole MCCB, contactor power contacts, and Overload Relay.
2. A single pole MCB is used for the control circuit. A single-phase power supply for the control circuit is connected through this single-pole MCB.
3. The contactor coil is connected to the single-phase power supply through the NO(Normally open) contact of a 24V Relay.
4. The 24V relay coil is connected to the 24V DC power supply through the proximity sensor.
5. Here, the positive terminal of the proximity sensor is connected to the positive terminal of the 24V DC power supply. The output terminal of the proximity sensor is connected to the positive terminal of the relay coil. And, the negative terminal of the sensor, relay coil, and the power supply are connected together to complete the circuit.

Working Principle

First of all, when an object is detected by the proximity sensor, it sends an output signal. The output signal from the proximity sensor closes the circuit, allowing current to flow to the relay coil.

Once the 24V relay coil gets energized by the signal from the proximity sensor, the Normally Open (NO) contact of the relay closes, allowing current to flow to the contactor coil.

The energized contactor coil closes the contactor power contacts, allowing three-phase power to reach the motor. The motor starts operating as it receives the three-phase power supply.

The overload relay monitors the current flowing to the motor. If the motor draws excessive current (indicative of an overload condition), the overload relay will trip, cutting off power to the motor to prevent damage.

When the object moves away from the proximity sensor, the sensor opens the circuit so the relay coil de-energizes, causing the NO contact to open. This cuts off power to the contactor coil, causing the contactor to open and disconnect the three-phase power from the motor and the motor stops running.

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