Slipcontacts

Slipcontacts are a class of electrical contact interfaces used in rotating assemblies to transfer power and signals between stationary and rotating parts. They form the sliding counterpart to a slip ring or other rotary joint, using a conductive element pressed against a rotating conductor.

Construction and operation: A stationary housing contains one or more spring-loaded conductive elements—often carbon-based brushes or metal alloy pins—that press against a rotating conductive surface, such as a slip ring or commutator. Relative motion causes a sliding electrical interface; current is carried through the brushes to or from the ring. Contact force is controlled to balance wear against contact resistance. Some designs incorporate insulating separators and lubrication to reduce wear and arcing.

Materials and variants: Common slipcontacts use carbon or graphite brushes for longevity and low wear, sometimes with metal paths for higher current. Metal brushes or composite contacts may be used in high-speed or high-current systems. Sealed or dust-proof variants exist for harsh environments. Lubricants or dry coatings may be employed to further reduce wear and noise.

Applications: Slipcontacts are used in rotating equipment where continuous electrical connection is required, such as power and signal transfer in wind turbines, robotics joints, conveyor systems, machine tools, stage lighting, medical imaging gantries, and research apparatus.

Advantages and limitations: They provide a simple, compact, and relatively inexpensive means to transfer electricity across a rotating interface and support multiple circuits. Limitations include wear and tear, variation in contact resistance, potential arcing at higher currents, and the need for periodic maintenance. In demanding applications, sealed slip ring assemblies or alternative solutions may be preferred.

See also: slip ring, brush gear, rotary joint.