We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Electrical

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Is a Repulsion Motor?

By Ray Hawk
Updated: May 17, 2024
Views: 29,749
References
Share

A repulsion motor is a type of electric motor that is designed to provide a high level of torque or rotational force upon start up, and to have the capability of easily reversing the direction of rotation. It is an alternating current (AC) motor that uses a series of contact brushes which can have a varied angle and level of contact for changing torque and rotational parameters. These motors were widely used in early industrial equipment, such as drill presses until the 1960s that required a large amount of slow rotational force, and in micro-control systems, such as for traction motors on model railroads. As of 2011, they have mostly been replaced by less complex induction motor designs with circuitry controls that are more reliable and easier to manufacture and maintain.

The design of a repulsion motor has both an electrical winding for the stator and rotor assembly and no permanent magnets to generate an electro-magnetic field. Electrical brushes are positioned over the rotor assembly through a commutator, and current is passed through them to the rotor while in contact to start the motor. Once the repulsion motor reaches a high rate of speed, the brushes are usually withdrawn and the motor acts as a typical induction motor. This gives the repulsion motor high torque at low speeds and standard motor performance at high speeds. A shorting mechanism is also built into the motor to break the connection to the commutator so that it can operate as an induction motor and also have the ability to reverse rotation.

The drawbacks to the design of the repulsion motor include the complex mechanical design of the contact brushes and the fact that it was modeled after early direct current (DC) motor functionality. It is a single-phase motor, meaning that it uses AC current that is run through a stator assembly with one electrical winding, but the stator itself has up to eight magnetic poles. The rotor assembly resembles the way that an armature is built into a DC motor, so it is often referred to as an armature in engineering fields, and this is where the commutator and brushes come into contact to control torque and direction of rotation.

The direction in which the brushes approach or contact the commutator and, therefore, the rotor, as well as their physical proximity to it, determines the motor's speed by creating a repulsion effect with competing magnetic poles. The armature and stator each have their own sets of magnetic poles and are offset by roughly 15 electrical degrees from each other, which creates a magnetic repulsion effect that starts the rotor rotating. The location of the brushes is critical in the proper function of the repulsion motor, because, if the brushes are at direct right angles to the stator assembly, the poles cancel each other out preventing magnetic flux, and no rotation torque exists.

While modern electrical circuitry has replaced many repulsion motors with induction motors that have similar control features, the repulsion motor is still used in some fields due to its ability to generate a large amount of torque at slow speeds. These include such applications as printing press drives and ceiling fans, or blowers for environmental controls that have slowly rotating fan assemblies. Variations on the original design of the repulsion motor include incorporating typical induction performance principles into it, such as the repulsion start induction motor, repulsion induction motor, and compensated repulsion motor.

Share
About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Link to Sources
Discussion Comments
Share
https://www.aboutmechanics.com/what-is-a-repulsion-motor.htm
Copy this link
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.