Slip Rings and Their Importance in Motors

A slip ring is a common component of many electromechanical systems, permitting power and electrical signals to be transferred from a stationary structure to one that is rotating. When implemented within a system, a slip ring may benefit mechanical performance, streamline operations, or mitigate the amount of dangling wires that may be present within an assembly. Slip rings can also come in a variety of designs, typically varying depending on the application that they were made for and the role that they serve.

For their basic functionality, slip rings often feature a stationary brush that rubs against the outer diameter of a rotating metal ring. As the brush is typically constructed from a conductive material such as graphite or metal, electric current is relayed through the brush to the metal ring. In some instances where there is more than one electrical circuit present within a system, more rings and brushes may be stacked alongside the rotating axis. Despite the brush commonly being the rotating element, some slip ring designs may rotate the ring against stationary brushes.

Motors are a common application for slip rings, though they are not used for transferring power in such cases. When acting as an AC motor component, the slip ring provides resistance to the rotor windings. Known as a wound rotor motor, such AC motors take advantage of three copper slip rings that are mounted to their motor shaft. With three phases of rotor windings, each slip ring is connected to a separate phase and is insulated from the shaft. The brush of the slip ring is composed of graphite, and it will often be attached to some form of resistive device. When the motor is in operation, the slip ring rotates alongside the rotor, allowing for the brushes to maintain ring contact for the means of transferring resistance to the windings.

As wound rotor motors are a form of asynchronous motor, they feature a rotor and stator electrical field that will revolve at different paces. With the addition of resistance as provided by the slip rings, the rotor current can be more aligned with the stator current, resulting in increased torque generation. As slip rings begin to lose their efficiency when the motor reaches full speed, such components are only used during the start-up process and will short out and lose contact soon after.

Due to the functionality that a slip ring provides for motors, such components are often compared to commutators. Despite this, the two part types are quite different in both appearance and functionality. When used within AC motors specifically, the slip ring serves to continuously transfer resistance to align currents for more optimal operations. Meanwhile, a commutator is a part that is common to DC motor equipment and may serve for reversing polarity in armature windings. Furthermore, slip rings are ring shaped components while the commutator is segmented and connected to motor parts through a different method.

While slip rings are useful for the operations of AC motors, they may also be used for countless other applications such as temperature sensors, aerodrome beacons, telemetry systems, wind turbines, and much more. At Infinite Industrials, we are your sourcing solution for top quality industrial parts and slip ring components that have been sourced from leading global manufacturers that we trust. As the only independent distributor with a no China sourcing pledge, we ensure that every purchase ships alongside its qualifying certifications or manufacturing trace documentation as applicable. Furthermore, every item is rigorously tested, inspected, and cross-referenced prior to shipment for quality assurance. If you are interested in any of our offered components and would like a quote for your comparisons, fill out and submit an Instant RFQ form through our website today and a dedicated account manager will reach out to you in just 15 minutes or less, 24/7x365.