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, rotating electrical connectors, collectors, swivels, or electrical rotary joints, are commonly found in electric motors, electrical generators for AC systems and generally in all rotary systems with electrical connections of sensors and receptors.
AAC has developed a set of test devices that enables to test components and materials for slip-rings or potentiometers on simple components: e.g. just a wire =brush and a ring with v-groove can be sued to compare different coatings, surface finishes. On the other hand, for potentiometers just the grip and the ring are needed and loads downto 10mN can be realised.
The exact specification of each chamber relevant for electrical sliding contact materials can be found in the facility descriptions. They cover possibilities to select best material candidates for sliding contact applications in space (electro-tribological testing of material pairings in adequate environment, post analysis of sliding surfaces / wear tracks). Usually with best material pairings breadboards and engineering models are manufactured which can also be tested in same environments on their electrical and mechanical behaviour (torque of whole slip-ring or cable wrap stack, arcing resistivity, electrical conductivity). Finally, testing of flight hardware may be performed in a thermal vacuum chamber placed in a clean-room class 10000.
Material tests & material selection
Millitribometer in vacuum chamber
Slip-ring vs. wire or disc vs. wiper
Low speed; air/vac/vac+HT
„Semi-life“ tests of slip-ring vs. wire; high speed; air
This vacuum chamber is made for testing of single slip-rings or potentiometers. The chamber with the pumping unit consisting of a rough vacuum pump and a turbo molecular pump can be seen in the photo below. Also the rotating shaft with motor (and gear) is visible (bottom of the facility). The shaft contains also a torque measurement cell. Furthermore an angle sensor is mounted.