[Wiring Diagram] 3 Phase Motor Control from Multiple Locations

Hey, in this article, we are going to see the wiring diagram for controlling a 3-phase motor from Multiple Locations. This type of arrangement is used in both industrial and commercial sectors. It is basically used when a single control point is insufficient. In industries where large machinery or equipment is used, such as manufacturing plants, refineries, or processing facilities, multiple control points are required to increase operational efficiency and versatility.

Having multiple control points provides a backup option also. If one control point fails or becomes inaccessible, another control point can help a lot so the operation will continue without significant disruption. Multiple Control Points provide Remote Operations for the motor. In situations where motors are located at a distance, it allows operators to control the motors without the need to travel long distances.

Wiring Diagram

Here, you can see the wiring diagram for controlling a 3-phase motor from multiple locations.

Apparatus Used

• 3 Pole MCCB - 1 PCs
• Single Pole MCB - 1 PCs
• 3 Pole Contactor - 1 PCs
• Overload Relay - 1 PCs
• NO Push Button Switches - 3 PCs
• NC Push Button Switches - 3 PCs
• 3 Phase Motor - 1 PCs

Connection Description

1. As you can see the main three-phase input power supply is connected to a 3-pole MCCB. The output of the MCCB is connected to the input of the 3-pole contactor. 
2. The output of the Contactor is connected to the Overload Relay(OLR) and then the output of the OLR is connected to the 3-phase motor.
3. Now, a single-phase MCB is used to protect the control circuit. It takes one phase from the 3 phase supply and the neutral.
4. The neutral output from the MCB is directly connected to the neutral terminal of the contactor coil.
5. The phase output from the MCB is connected to the NC contact terminal of the Overload Relay. Then another terminal of the NC contact is connected to the input of the NC push button switch(STOP Switch). All the push button switches are connected end-to-end means in a series combination.
6. Then the final output of the NC push button switch is connected to the input of all the NO Push button switches.
7. Now, output from all the NO push button switches(START Switch) is connected to the Phase terminal of the Contactor Relay.
8. The phase terminal of the contactor coil is also connected to the output of the NC push button switch through the auxiliary NO contact terminals.

Working Principle

Here, the 3-pole MCCB is used as the main circuit breaker for the entire motor control circuit. It provides overcurrent protection and can be used to disconnect power to the entire motor circuit when needed. The single-pole MCB is used to protect the control circuit. It acts as a secondary protection device, providing overcurrent protection specifically for the control components and wiring. 

The 3-pole contactor is basically an electromechanical switch. So here it is used to control the power supply to the 3-phase motor. It has three sets of contacts, one for each phase, and is typically controlled by the control circuit to open or close the power circuit to the motor. The overload relay protects the motor from excessive current consumption. If the current exceeds a set limit the overload relay opens the contactor so the power to the motor will be disconnected and it will prevent damage due to overheating.

The NO push button switches are basically momentary switches that are normally open. When they are pressed, they close the circuit, allowing current to flow. In motor control, these buttons are used for start commands. For example, pressing the start button initiates the control circuit to close the contactor and start the motor. 

The NC push button switches are also momentary switches that are normally closed. When they are pressed, they open the circuit, interrupting the current flow. In motor control, these buttons are often used for stop commands. For example, pressing the stop button opens the control circuit, de-energizing the contactor and stopping the motor.

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