How to assemble a 3-phase motor DOL starter (direct on line) circuit

Summary

In this video, the host demonstrates how to assemble a Direct Online (DOL) starter circuit for a 3-phase motor or water pump, explaining each step in detail. Using components like a Mitsubishi contactor, overload, push button stop, pilot lamps, and MCCB, the setup covers the wiring and connection process from the input to the power circuit. The video explains the importance of correct wire connections, overload protection, and proper control circuit wiring. Aimed at users working with motors up to 5.5 kW, the tutorial offers a practical guide for setting up a DOL starter system safely and effectively.

Takeaways

• 😀 A Dol Starter Circuit is used to assemble a direct online (DOL) motor starter, commonly for 3-phase motors or water pumps.
• 😀 The primary materials required for the assembly include a Mitsubishi contractor, overload protection, 3-phase motor, pilot lamps, and push buttons.
• 😀 Proper wiring of the input from the PLN (R, S, T, and Neutral) into an MCB (Molded Case Circuit Breaker) is essential for safety.
• 😀 The MCB controls the circuit, and the output from the MCB should be connected to the overload protection circuit.
• 😀 The stop button in the control circuit should be connected to the MCB, and the push button controls the start and stop of the motor.
• 😀 The start button of the circuit is locked in place using contacts 43 and 44 to ensure the motor operates properly.
• 😀 Proper jumper connections are critical for connecting components such as the MCB, overload, and contactor.
• 😀 Indicator pilot lamps are used to signal the operational status of the motor, such as the 'star' pilot lamp turning on when the motor is activated.
• 😀 The overload protection needs to be connected to a Normally Open (NO) contact, ensuring it cuts off when an overload is detected.
• 😀 The wiring sequence for the power circuit ensures proper motor operation, with phases R, S, and T connected to the MCB and the 3-phase motor correctly wired.
• 😀 This DOL starter system is typically used for motors up to 5.5 kilowatts and ensures that all control and power circuits are properly set up for safe operation.

Q & A

What is the main focus of this tutorial video?

The tutorial focuses on assembling a Dol (Direct Online) starter circuit for a 3-phase motor or water pump, demonstrating the wiring and setup for such a system.

What materials and tools are used in this assembly?

The materials and tools used include a Mitsubishi contactor, overload protection, a 3-phase motor, push buttons (stop/start), pilot lamps (red, orange, green), MCCB, MCB, and input connections from PLN (R, S, T, and neutral).

What is the purpose of the MCB in this circuit?

The MCB (Miniature Circuit Breaker) is used to protect the control circuit from overloads, ensuring the safety of the system by disconnecting power in case of a fault.

Why is the contactor coil rated at 220V?

The contactor coil is rated at 220V because it is designed to operate with a 220V control circuit. This voltage ensures that the contactor will activate when needed to control the 3-phase motor.

What is the function of the overload relay in this system?

The overload relay provides protection to the motor by monitoring its current. If the motor draws too much current (indicating a fault or overload), the relay disconnects the motor to prevent damage.

Why is the normally closed (NC) terminal of the overload relay important in this setup?

The NC terminal of the overload relay ensures that, when the motor operates normally, the circuit remains closed. If an overload occurs, the NC terminal opens, cutting off the power to the control circuit and stopping the motor.

What role do the pilot lamps serve in this circuit?

The pilot lamps indicate the status of the system. The red pilot lamp shows the motor is in star mode, the orange lamp indicates an overload condition, and the green lamp signals that the motor is operational.

How is the locking mechanism for the contactor wired?

The locking mechanism is wired between the start button and the contactor’s NO terminals (3 and 4), ensuring that once the start button is pressed, the contactor remains engaged until the stop button is pressed.

Why is the order of wiring important when connecting the three-phase power to the motor?

The order of wiring is crucial because connecting the phases in the wrong sequence can cause the motor to run in reverse or not start at all. Proper phase order ensures correct motor rotation and operational efficiency.

Which phase colors are used for the connections in the circuit?

The phase colors used are black for R, brown for S, and gray for T. These colors follow the standard color coding for three-phase electrical systems.