Asynchronous motors are one of the most widely used types of motors that convert electrical energy into mechanical energy, and three-phase asynchronous motors in particular have a very broad range of industrial applications. The term “three-phase” refers to the three-phase alternating current supply required for their operation, which enables reliable performance in high-power applications. With strong torque generation, energy efficiency, and durability, three-phase asynchronous motors are preferred in many areas—from crushing plants to pumps and compressors, from fans to conveyor systems. Rotor motion can be controlled with different methods, allowing the motor’s performance to be adjusted according to need, making them indispensable in industrial facilities, heavy-duty applications, and systems requiring continuous operation.

Three-phase asynchronous electric motors are the most widely used type of motor in industry. Thanks to their reliability, low maintenance needs, and cost-effectiveness, they account for approximately 80% of all electric motor usage worldwide.

Structure

  • Stator: Contains three-phase windings. When powered by a three-phase AC supply, it creates a rotating magnetic field.

  • Rotor:

    • Squirrel-cage rotor: Simple, robust, requires little maintenance.

    • Wound rotor: Adjustable starting torque, used in more specialized applications.

Working Principle

  1. Currents from the three-phase supply flow through the stator windings with a 120° phase difference.

  2. These currents generate a rotating magnetic field in the stator.

  3. The rotating field induces voltage in the rotor → current flows → Lorentz force makes the rotor turn.

  4. Rotor speed is slightly lower than synchronous speed → this difference is called slip.

Key Features

  • Power Range: Manufactured from 0.09 kW up to megawatt levels.

  • Voltage: Typically 220/380 V or 400/690 V (star–delta connection).

  • Speed: 750 – 3000 rpm (depending on pole count).

  • Efficiency: High, especially in IE3 and IE4 class motors.

  • Durability: Long service life, robust construction, easy maintenance.