Burns created by improper electric grounding while bearing is stationary.
Electric arc bearing damage.
Once electric arc bearing damage has begun excessive vibrations increased heat increased noise levels and the reduced effectiveness of the lubricant will combine to shorten a bearing s service life.
The extent of damage to bearings depends upon the amount of energy and its duration.
This electric discharge can occur at very low voltages and may cause severe pitting of the bearing or shaft surfaces or both.
W hen bearing fluting or other evidence of electrical damage was clear the cause was frequently believed to be due to some local condition relating to power supply grounding or to a specific vendor or product.
This has distracted many from the general and w idespread incidence of this class of bearing damage.
In such a case the pitting may look blackened because of oil deposits.
But when noise occurs the damage has usually become substantial enough that failure is imminent.
Electric arc fluting fluting caused by electric current roller with electric arc burns adhesive wear on bearing inner ring roller flats adhesive and skidding wear on raceway surface roller end with adhesive wear cage pocket wear from excessive roller movement wear at small ends of cage pocket and on roller bridges scalloping marks in the cup.
There s no definitive way to predict whether or when bearing currents will occur.
In extreme cases damage may occur very rapidly.
When a stray current in a machine uses a bearing as its path to ground the resulting damage is referred to as electric arc bearing damage.
The damage usually appears on the surface of rings and rolling elements and is similar to that produced by electric arc welding.
Either visible regular patterns flutting or.
By some accounts electrical damage damage caused by electric discharge machining is the most common cause of failure for ac motors driven by vfds.
Arcing can be useful but in some instances unwanted arcing causes damage to industrial structures like bearings.
Series of axial burns caused by electric current passing through the bearing while rotating.
Improper fit damage electric current damage fluting.
When it does the cause may be difficult to diagnose as pitting of the bearing surface is followed ultimately by wiping which may obscure the original pitting.
Random electrical currents which come from multiple sources such as wiring insulation static electricity from operating equipment and so on will damage bearings.
