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Rojony Khatun
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Last updated: October 2, 2025

Automatic 3-Phase Motor Control Wiring with Auto-Trip Protection

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3 Phase Motor 2Hp

3 Phase Motor 2Hp

Three-phase electric motor with 2 horsepower

Single Phase Contactor

Single Phase Contactor

Electromagnetic switch designed for controlling single-phase electrical loads

3 Phase Motor Overload Relay

3 Phase Motor Overload Relay

Protective relay that trips when motor current exceeds safe limits

Single Phase On-off Push Switch

Single Phase On-off Push Switch

Push-button switch to turn single-phase devices ON or OFF

single-Phase Ampere Meter

single-Phase Ampere Meter

Device that measures and displays amperes in a single-phase electrical system

[single-phase-ampere-meter]

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simple 3-phase Motor Control Circuit

Learn simple automatic 3-phase motor control wiring with auto-trip, overload relay, contactors, and push buttons for safe and reliable motor operation.

industrial motor control circuit

Auto-3 phase motor control with auto-trip protection will allow safe and reliable operation, where the motor will automatically be disconnected in case of overload or fault. The system allows the motor operation to be constant and safe using contactors, an overload relay, and push-button control.

contactor motor starter diagram

A basic automatic 3-phase motor control with auto-trip provides a way of operating the motor safely and avoiding overloading. Components of the system are the main contactor, start/stop push buttons, overload relay, auto-trip mechanism, and 3-phase connections to the motor. The contactor becomes energized when the start button is pushed and provides a 3-phase power to the motor. The overload relay constantly maintains a check on current flow; should a high current flow be detected, then it sends the auto-trip mechanism into action, and then it breaks contact on the motor before it can be harmed. The stop button enables an operable motor stop. This arrangement provides safe control of the motor, guarantees against short circuiting or overloading, and provides an easy automatic mode of control. It finds extensive application in industrial pumps, conveyors, compressors, and other equipment that needs high-quality 3-phase motor operation. Appropriate wiring, phase sequence check, and testing are the key to operational safety and decreased motor wear.

Work & Installation (Input → Output Summary)

  • 3-Phase Supply enters motor starter panel.
  • Main Contactor energizes when the start button is pressed, supplying power to the motor.
  • Overload Relaycontinuously monitors motor current.
  • Auto-Trip Mechanism disconnects motor if overload occurs.
  • Stop Push Button allows manual motor disconnection.
  • Motor rotates safely, driving a mechanical load.
  • System automatically protects the motor from overcurrent faults.

Testing & Final Adjustments

  • Verify insulation and wiring connections for mains and motor.
  • Check phase sequence for correct motor rotation.
  • Press start button; ensure motor starts smoothly.
  • Observe overload relay; simulate overcurrent to test auto-trip function
  • Press stop button; confirm motor stops manually.
  • Inspect contactor operation and ensure no simultaneous faults.
  • Test MCB/fuse and ensure proper protection.
  • Verify earthing and secure all connections.
  • Ensure smooth motor operation under load without sparks or vibration.
  • Record results for operational reliability and maintenance reference.

Frequently Asked Questions - simple 3-phase Motor Control Circuit:

What is automatic 3-phase motor control with auto-trip?

A motor control system that automatically protects the motor from overload using contactors and overload relay.

Why use auto-trip protection?

To prevent motor damage from overcurrent or short circuit conditions.

Which devices are required?

Main contactor, overload relay, start/stop push buttons, auto-trip mechanism, and motor connections.

How does auto-trip work?

Overload relay detects excessive current and trips the contactor to disconnect the motor.

Is this for 3-phase motors only?

Yes, typically used for 3-phase induction motors in industrial applications.

How to start and stop the motor?

Press the start button to energize the contactor and stop button to disconnect manually.

Can auto-trip be reset?

Yes, most overload relays have a manual or automatic reset feature.

Where is this system used?

Industrial pumps, conveyors, compressors, and machinery requiring safe 3-phase motor control.

Is earthing necessary?

Yes, for safe operation and protection of personnel and equipment.

How to maintain the system?

Regularly check wiring, contactor operation, overload relay, and auto-trip mechanism for reliability.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.