Shaft Voltage Grounding

Grounding Brushes


  • Inserted into coupling

  • Removed from assembly

  • Sohre Turbomachinery┬« Inc. provides high performance, high reliability bristle type fiber brushes for use in shaft grounding (shaft earthing) of all types of stray electrical shaft currents. The brushes can also be used for instrument signal transmission and generator or electric motor on-line diagnostic work.

    Installable and serviceable during operation. For damage prevention by measuring and grounding stray currents of any origin in: Turbines, Compressors, Generators, Motors, Gears, Ship Propeller Shafts, or other rotating equipment. Because no maintenance or cleaning is usually necessary, the fiber brushes are especially useful in radiation control areas.

    Failure to properly ground rotating shafts can result in unexpected outages and expensive damage, such as bearing failure due to spark erosion (sometimes called electrolysis). Catastrophic wrecks are a possibility. Technical papers on this subject are available.

    In addition to their use as shaft grounding brushes (earthing brushes), the brushes are also suitable for the transmission of instrument signals from a rotor without the use of special slip rings. This allows continuous monitoring of parameters such as voltage, vibration and torque during normal field operation.

    Grounding Brush Features

    1. For shaft grounding, shaft earthing of all types of stray shaft currents-such as found on turbine generators, gears, pumps, turbines, compressors, electric motors, ship propeller shafts or other rotating equipment. Failure to properly ground rotating shafts can result in expensive damage such as damage due to spark erosion (electrolysis). Also suitable for generator or electric motor diagnostic work.
    2. Brush is suitable for transmission of instrument signals from the rotor without the need of special slip rings. This allows continuous monitoring of vibration, torque etc., during operation.
    3. Bristle-type fiber brush element, made of silver and gold composite. Bristle element is replaceable during operation.
    4. Length of brush and installation position and location may be varied.
    5. Large and small sizes; special designs.
    6. Working parts are removable during operation without risk of contacting adjacent moving parts. Remove screws at "X" to pull entire brush assembly out of brush casing (see Schematic Drawings).
    7. Wear and position indicator.
    8. Brush voltage is insulated from casing, allowing voltage and current monitoring and selective grounding.
    9. Provision to raise fiber brush from shaft during operation, to inactivate if contact is not desired.
    10. Operates dry or with oil spray, oil splash (preferred), or immersion.
    11. Shaft surface velocity: In operation to approx. 500 ft/sec (150 m/sec).
    12. Wear life: Fiber brushes have been in continuous operation for years with minimal wear, and without loss of electrical performance. Design rating: 1 year continuous at rated current.
    13. Minimal axial shaft space required: approx. 0.75" standard.
    14. Suitable to 400 deg. F.
    15. Oil and gas tight assembly available.
    16. Nonmagnetic construction.
    17. Meets API Standard 612.