VÒNG DIỆT ĐIỆN ÁP TRỤC EARTHRINGS

With the advent of more and more VSDs becoming used globally, what is the most effective and economical solution?

The answer is earthing rings, or Bearing Protection rings. – These rings consist of very thin micro-fiber that redirects shaft currents and provides a reliable, very low- impedance path from shaft to frame, which bypasses the motor bearings entirely. The earthing ring is attached to the electric motors bearing housings.

Once installed, the earthing rings require no maintenance. Unlike conventional shaft grounding brushes, its conductive microfibers work with virtually no friction or wear. They are unaffected by dirt, grease, or other contaminants, and last for the life of the motor, regardless of motor speed.

In overseas trials the results show surface wear of less than 0.001 in. per 10,000 hr of continuous operation, and no fiber breakage after 25 million direction reversals.

For almost a decade these earthing rings have been extensively used in USA, UK and more recently Australia. There are thousands of case studies that show the positive effects of using these rings. The rings are seen as a solution to these problems, as well as an insurance against unforeseen problems.

During changes in load conditions and during adjustments to their drive parameters it was found that many motors exhibited increased shaft currents after their most recent repair. This is why it is termed "The Ghost", since it can never be determined when its effects will drastically increase and rapidly destroy bearings. It is of utmost importance that industry protects itself against this so called "Ghost", especially in regard to their critical motors.