A slip ring (in electrical engineering terms) is a method of making an electrical connection through a rotating assembly. Slip rings, also called rotary electrical interfaces, commutators (albeit falsely), collectors, swivels or electrical rotary joints, are commonly found in electrical generators for AC systems and alternators.
A slip ring consists of a conductive circle or band mounted on a shaft and insulated from it. Electrical connections from the rotating part of the system (such as the rotor of a generator) are made to the ring. Fixed contacts or brushes run in contact with the ring, transferring electrical power or signals to the exterior, non-rotating part of the system.
This system is similar to the brushes and commutator found in many types of DC motors. Slip rings can also be used where electrical power or signals need to be transferred to a rotating device, such as a rotating visible light beacon. (In high speed or low friction environments, rotary transformers are often used instead of slip rings.)
Popular Manufacturers of Slip Rings include: Electro-Tec & Poly-Scientific of Blacksburg, Virginia (now both owned by Moog Inc.), and Schleifring of Germany