Slip Rings

Slip rings are metal rings that provide a continuous electrical connection through brushes on stationary contacts. They are generally mounted on the rotating part of a machine. The electrical connection can be via wiping contacts, mercury, infrared transmission, radio transmission, etc. Configuration, performance and features are important specifications to consider when searching for slip rings.

Important configuration parameters include hardware configuration, slip ring configuration, and contact type.  Choices for hardware configuration are two-piece or one-piece.  A two-piece slip ring has a separate brush block and rotor.  A one-piece slip ring is an integral unit with bearings.  Slip ring configuration choices include drum type or pancake type.  In drum type slip rings each ring lies along the drum axis, like threads on a bolt.  In pancake configuration the rings are concentric, like grooves on a phonograph record.  Contact choices include sliding or wiping contacts, mercury contacts, or wireless.  Sliding or wiping contacts have rotating and stationary contacts that slide or wipe against each other. Mercury contacts typically have low electrical noise. Wireless or non-contact transmission contacts include infrared, radio, etc.

Important performance specifications to consider when selecting slip rings include operating speed, number of circuits, number of signal or voltage circuits, maximum voltage for the signal circuits, maximum current for the signal circuits, number of power or current circuits, maximum voltage for the power circuits, maximum current for the power circuits, and operating temperature.  The total number of circuits includes all signal/voltage and power/current circuits. In some slip rings a circuit can be used either way and is counted only once. If there is a return path or ground then it is a separate circuit. Circuit, ring and way are all synonymous.  Signal or voltage circuits include signal or low power circuits.  Power or current circuits include power or high current capacity contacts.  Common features for slip rings include electrical connectors and through-hole bore.  Electrical connectors are used for quick disconnect. A through-hole bore allows routing for coolant, hydraulic, pneumatics lines, etc.

• How a Slip Rings Works
  A slip ring is a rotary coupling used to transfer electric current from a stationary unit to a rotating unit. This is accomplished by either (1) holding the center core stationary while the brushes...
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• Magnetic Field Sensors as Speed Monitors
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• Sensing without wires
  Wireless sensing solves many problems, but introduces a few of its own. A factory building I-beam reflects transmission of wireless sensor data to a digital readout. The readout receives both the main...
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