Multipole Electric Motors: What They Are and How They Work

What Are Multipole Electric Motors?

Multipole electric motors are a type of electric motor that have multiple magnetic poles in their stator or rotor. Unlike standard two-pole motors, which have one north and one south pole, multipole motors have additional poles—such as four, six, or even more—arranged symmetrically around the motor.

These motors are widely used in industrial applications where high torque and efficient operation at lower speeds are required.

How Do They Work?

The operation of multipole electric motors is based on electromagnetic induction. The motor consists of:

1. Stator – The stationary part of the motor, containing coils that generate a rotating magnetic field when current passes through them.
2. Rotor – The rotating component that interacts with the stator’s magnetic field to produce motion.

When AC or DC current is supplied to the motor, the stator generates a rotating magnetic field that induces motion in the rotor. The number of poles in the motor determines the speed at which this field rotates, following the formula:

Where:

• n = Synchronous speed (RPM)
• f = Supply frequency (Hz)
• P = Number of poles

As the number of poles increases, the synchronous speed of the motor decreases. For example, a two-pole motor operating at 60 Hz has a synchronous speed of 3600 RPM, while a four-pole motor would have 1800 RPM.

Advantages of Multipole Motors

• Higher Torque – More poles allow for greater torque at lower speeds, making these motors ideal for heavy-duty applications.
• Better Efficiency at Low Speeds – Multipole motors reduce the need for gearboxes in some applications, saving energy and maintenance costs.
• Reduced Wear and Tear – Operating at lower speeds can extend the lifespan of motor components.

Applications of Multipole Motors

• Industrial machinery (conveyors, pumps, compressors)
• Wind turbines
• Elevators and cranes
• Electric vehicles
• Robotics and automation