The SR20A_/T___/AX Slip Ring Assembly has 20 slip ring circuits in a weatherproof housing. It has a type A (2.500″ diameter) rotor, with Bendix PT connectors on the stator and rotor. The tachometer model has built-in encoder (tachometer) electronics.
- 20 slip ring connections
- Encoder rotation sensor
- Available with or without weatherproof seals
- Type A (2.500″ diameter) rotor
- Circular connectors on stator and rotor
- Instrumentation quality rings & brushes
- Sealed, corrosion resistant metal housing
- Lightweight and compact
The SR/ERT Series is used when a slip ring and/or a rotation sensor needs to be mounted at the end of a rotating shaft. The gold alloy slip rings are used to make high quality electrical connection to strain gages, thermocouples, or other sensors that have been installed on rotating machinery. Current capacity is 0.5A per connection and the maximum peak resistance variation is 0.1 ohm. The rotation sensor is used to measure rotational velocity, angular position, and direction of rotation. The rotation sensors do not use any of the slip ring connections.
The housings are approximately three inches long. They weigh about 15 ounces. The rotors are made from high strength stainless steel. The stators are lightweight, nickel-plated, aluminum. Threaded holes are provided for attaching a rotation restraint. Connection information is permanently engraved on the housing. Circular connectors or solder terminals are offered as wiring terminations.
All housings in this series have been designed to accept contacting rotary seals. Units ordered with these seals (choice W) are completely weatherproof and can survive days of total submersion. The seals limit operation to 2000 rpm maximum. Most wet weather applications, like automotive wheels, are within this range. For higher speeds in dry conditions, order units without the contacting rotary seals. Units without seals are capable of the following speeds:
- 20 rings – 4,000 rpm
Unit torque with seals is 21 inch-ounces. Unit torque without seals is three inch-ounces. If the application requires a high speed, weatherproof slip ring & encoder, consider units with non-contacting labyrinth seals in the SR/E512 series.
Rotation sensor choices E256, E360, E500, & E512: Four optical encoder resolutions are offered, see the table below. Each of these encoder choices has 4 outputs, shown graphically below. Outputs A and B are in quadrature (exactly 90° out of phase). Output I is an index pulse. Output A+B is the exclusive OR of A and B, which doubles the basic resolution of the encoder. The outputs, 0 to 5 volt pulses, can drive TTL loads. The encoders will operate from a +5 to +20 Vdc, 100 mA power supply. Temperature range is -40F to +212F. The encoders have metal code wheels and rugged electronics so they tolerate shock and vibration. They are also protected from incorrect wiring up to 20 volts. Accuracy of encoder systems is 0.25° (maximum cumulative error).
Rotation sensor choices T256, T360, T500 & T512: Additional encoder electronics can be built into the encoder units. The electronics adds two analog outputs, a voltage proportional to shaft velocity (similar to a tachometer) and a voltage proportional to the angular position of the shaft. The analog outputs are easier to record than the digital encoder outputs, which require high sampling rates. Both analog outputs are updated at each pulse of encoder output A, so they are instantaneous, not average values. The encoder electronics will operate from a +8 to +18 Vdc, 200 mA power supply.
Temperature range is -40F to +185F.
Full scale for the angular position output is +10V for rotation in either direction.
Full scale for the velocity output is +10V for rotation in one direction and -10V for rotation in the opposite direction. Two velocity sensitivities and direction of rotation are usually programmed into each unit. Two pins in the stator connector are designated as option pins, through which the user selects 1 of 4 combinations. For example, units used on our torque wheels are normally programmed to output 10V at 1000 rpm with option pin #1 open. With option pin #1 grounded, full scale is 1800 rpm. Option pin #2 sets the polarity, or direction of rotation, viewing the end of the shaft. With pin #2 open, CW
rotation results in a positive velocity output. When pin #2 is grounded, CCW rotation results in a positive velocity output.