We come across many objects that rotate in our daily lives. How does power transfer when a device is in constant rotation? The electromechanical device that allows power and data to be transferred from a stationary system to a rotating one is a slip ring. Some of the examples of applications of slip rings include truck booms, grain bins, wind turbines, pallet wrappers, amusement rides, etc.
Advantages of using a slip ring
- Prevents wires from tangling
- Smooth transfer of power and data between rotary systems
- Can handle a wide range of high-power rotary applications
How does a slip ring work?
A slip ring rotates under a variety of speeds depending on the application. The slip ring rides along a center shaft and sits on a base plate. The base plate or mount is held stationary and the shaft rotates in the center. This allows the slip ring to transfer power from a stationary system to a 360-degree rotating unit, completing the circuit.
Slip ring configuration
A slip ring consists of 2 main components: rings and brushes.
- The ring provides the circuit path and is made up of an electrically conductive material such as brass, plated silver or coin silver, and is usually mounted on, but insulated from, a center shaft. The insulating material between the rings and between the ring and the shaft is made of nylon, phenolic plastic or other non-conductive material.
- The brushes sit on brush arms that are attached to the side posts that ride on the ring to provide the electrical contact, connecting the rotating and stationary parts of the assembly. The brush is made up of copper graphite or silver graphite. Although typically one brush pair per ring, amperage requirements may necessitate the use of four or even more pairs per circuit.
Depending on the customer requirements, rings are stacked along the center shaft with the brushes to provide the complete slip ring assembly. The wire leads from the brushes and from the rings are connected to electrical circuits. Slip rings can be enclosed using a cover to protect them from dust, moisture, and other elements to prevent malfunction.