Part 2 - How to Fix Shaft Currents

[@mauriceupton1474]

How effective are they when they get contaminants for example grease on them?

[@TechTrainTracks]

Thanks for your interest Maurice - much appreciated. Yes - a buildup of non-conductive contaminants such as grease can inhibit the effectiveness of shaft grounding rings and brushes. However, the proper installation includes a coating of colloidal silver which helps the grounding ring micro fibers to maintain contact and somewhat block contaminants. Also, if the grounding ring is installed during a rebuild, the grounding ring can be installed internally in the motor enclosure to prevent this contamination. And another way to look at your noted situation, is the externally mounted grounding ring is acting to prevent contaminants from entering the bearing and causing damage. Additionally, if shaft current test readings indicate the contaminants have blocked the shaft grounding ring fibers are no longer making sufficient contact with the shaft, it is a simple matter of cleaning the surfaces. And should a quick cleanup not prove effective, then a split-type grounding ring could be installed to replace the damaged grounding ring without removing or uncoupling the motor from the driven equipment. Finally, another available solution if the damaging shaft currents are coming from a high switching frequency IGBT drive (the most predominant drive type for many years), then inductive absorber coils could be installed on the power cables at the VFD which feed the motor. We have a new video explaining these inductive absorber coils.

[@mauriceupton1474]

ReedElectric Thanks, we use these and external brushes on ac and DC motors but greases and dusts take their toll, still get bearing damage but not as severe.

[@TechTrainTracks]

Maurice - have you watched our videos on the Inductive Absorption (CoolBLUE) method of solving shaft currents. They would likely work on your issues of shaft currents on AC motors run by IGBT type variable frequency drives.

[@SiElect1207]

Any PDF file of your manual? thanks

[@TechTrainTracks]

Apologize, but could you be more specific as to what "manual" you are looking for? If you are looking for a manual on Shaft Current Resolution methods, we can provide you with 2 such PDF files.

[@SiElect1207]

Yes can you share those manual to me? thanks and godbless

[@TechTrainTracks]

Here is a direct link to the Aegis Shaft Ground Ring method - www.est-aegis.com/bearing/index2.php And here is a link to the CoolBLUE Inductive Absorber method for most modern IGBT Variable Frequency Drive created shaft current damage www.coolblue-mhw.com/downloads/