3 Phase Motor and Timer Connection Diagram with DOL Starter

Here, in this article, we are going to see the connection diagram between a 3-phase motor and a Timer with a DOL Starter. This circuit will allow us to operate the three-phase motor in both Manual and Automatic Mode. We can manually On/Off the motor by using switches and we can operate the motor in an automatic mode with the help of a digital programmable timer which is also known as a programmable relay switch.

The combination of a 3-phase motor, timer, and Direct-On-Line (DOL) starter is commonly used in industrial and commercial applications where both the control and protection of a 3-phase induction motor are required. For example, in Industrial Pumping Systems such as water supply, irrigation, or wastewater treatment plants, DOL starters with timers are used to control 3-phase motors driving pumps. The timer is used to start and stop the motor at specific intervals or during periods of high demand which helps a lot to manage water distribution efficiently.

The other applications of the combination of a 3-phase motor, timer, and Direct-On-Line (DOL) starter are Conveyor Systems, Agricultural Equipment, HVAC Systems, Material Handling Equipment, Crushing and Mining Equipment, and many more.

Connection Diagram

Here, you can see the connection between a 3-phase motor, digital programmable timer, and DOL Starter Circuit. The DOL starter circuit is built with Contactor, Overload Relay, and Some Switches.

Components Used

• A Three Pole MCB(as Main Breaker)
• A Single Pole MCB(for control circuit protection)
• One NC Push Button Switch
• One NO Push Button Switch
• An Indication Lamp(Yellow Color to indicate Trip)
• A three-position selector switch(auto/manual)
• A Digital Timer(single-phase)

Wiring Description

1. The three phases from the input power source are connected to the input of the three-pole MCB.
2. The output from the MCB is connected to the main three-phase power input of the contactor.
3. The output of the contactor is connected to the three-phase motor.
4. The input of the control MCB is connected in any one phase(here R phase is used) of the output of the three-pole MCB.
5. The power input terminals of the timer are connected through the control MCB.
6. The NC and NO push button switches are connected to the Contactor Coil through the control MCB. Also, they make a holding circuit for the contactor coil.
7. The selector switch is connected between the Timer control terminals and the Contactor Switching Circuit.
8. The indication lamp is connected through the control terminals of the overload relay so it will glow when the overload relay is tripped.

Operating Procedure

1. First of all, both the main three-pole MCB and the Control MCB should be turned On.
2. If you want to control the motor manually then keep the selector switch in Manual or Position "1".
3. Then press the NO push button switch to turn On the Motor or press the NC push button switch to turn Off the Motor.
4. Now If you want to control the motor automatically then keep the selector switch in Auto or Position "2".
5. Then set timing or make programming on your timer according to your required motor starting and stopping timings.

Read Also: 

• VFD Wiring Diagram with Motor, Switches, and External Devices
• Dynamic Braking Resistor (DBR) Connection Diagram with VFD
• Submersible Pump Starter and Water Level Controller Wiring Diagram
• Float Switch Connection Diagram and Wiring with Water Pump
• Motor Control Circuit Forward Reverse | Wiring and Connection

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