Slip rings, also called rotary electrical interfaces, rotating electrical connectors, collectors, swivels, or electrical rotary joints, are commonly found in slip ring motors, electrical generators for alternating current (AC) systems and alternators and in packaging machinery, cable reels, and wind turbines. They can be used on any rotating object to transfer power, control circuits, or analog or digital signals including data such as those found on aerodrome beacons, rotating tanks, power shovels, radio telescopes or heliostats