Bearing Protector - Shaft Grounding Ring


Order Code: STA-RING 
Selectable Length (mm)
STA-Ring ASF Bearing Protector is developed with the latest technology to protect the engine and its equipment against undesired shaft currents and damages. It has patented technology that includes maxi conductive fiber hair that forms a very little impedance path from the shaft to the body (PATENT NO: 2013/04117). Bearing Protector can be considered as a Ball Bearing Protector Ring specified as per customer specified dimenions on request. Shaft Current Protection  is gaining importance among engine manufacturers with high importance. 

-Not effected from dust, dirt, lubricants.
-It can protect ball bearings from damage by means of hundreds of drain canals
-It is a low cost solution and can be applied to AC-DC motors at various power ranges.
-It does not require any maintenance.
-Can be applied to front and back shaft of engine.
-Preventing damage and wear at shaft by means of micro fibers and hairs.


STA-Ring Bearing Protector, a specific Roller Bearing Protector Ring, can be easily and quickly connected to all kinds of engines by means of 2 different production techniques.

  • STA-Ring ASF Bearing Protector Ring (Single Piece Shaft Grounding Ring)
  • STA-Ring ASF Split (2 pieces Grounding Ring) No need for dismantling of engine shaft and make coupling adjustment. A perfect Shaft Current Protector Ring easy to use and position.

Make sure that Engine Shaft and surface that STA-Ring ASF touches is cleaned from paint and similar dirts. (See Photo 1)

Center and rotate STA-Ring ASF Bearing Protector from engine shaft and mark the position of center holes. Open assembly holes on body by 3 mm drill (See Photo 2-3)


Connect STA-Ring ASF on body by means of electrically conductive screws. As electricity will pass over the screws, this item is very important.


STA-Ring ASF does not your provide your engine be grounded. It is very much necessary to make good grounding of your engine for being able to benefit from STA-Ring ASF (Photo 5).

Dimensions Between Ø 6,90 - Ø 150,90 mm
Width 7,50 mm
Hair Type % 100 Carbon
Body Alu
Certificate CE


  • For the purpose of reducing energy costs, frequency converters such as PWM, VFD have been started being used in Industry. This is causing a new type of damage among ball bearing defects.
  • During the operation of frequency converter a dv/dt (voltage / rising speed) is arising. This is forming an interferance capacitor between the stator and rotor of the engine. Accordingly the voltage on the engine shaft is continously increasing. Because of this increased voltage, shaft current tend to flow away from the system over the easiest path. This is where Bearing Protection Ring is used as follows.
  • The easiest and less resistant path over the system are the bearings. Accordingly shaft currents pass away over the roller bearings.Shaft grounding ring is very important at this stage to prevent the bearings from being damaged. 

Bearing Protector (Shaft Grounding Ring)

The current path shown with red color is a capacitive current pasing over  the roller bearings and eventually over the grounding line of the engine towards the earth. This path is forming a current passing over the roller bearings of the engine leading into a probable roller bearing defect
The path shown with gren shows the current matched from the stator coils to rotor. This path is causing damage from the pulley side of the engine’s roller bearing and couplings that connect the engine to the load. Current shown with yellow is the conduction over the engine roller bearings, engine shaft, coupling, ball bearing at the pulley side of the engine, discharging of load and eventually erthing of the driver. Current passing over this way has the potential to give damage to coupling as well as engine and roller bearing at the pulley side of the engine


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(Phone & Whatsapp: +90 533 347 35 08)