Electric Arc Bearing Damage

Either visible regular patterns flutting or.

Electric arc bearing damage. There s no definitive way to predict whether or when bearing currents will occur. For instance electrical pitting may be present in the linings of bearings where there is insignificant arcing. Random electrical currents which come from multiple sources such as wiring insulation static electricity from operating equipment and so on will damage bearings. 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.

Improper fit damage electric current damage fluting. 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. This has distracted many from the general and w idespread incidence of this class of bearing damage.

By some accounts electrical damage damage caused by electric discharge machining is the most common cause of failure for ac motors driven by vfds. Series of axial burns caused by electric current passing through the bearing while rotating. Burns created by improper electric grounding while bearing is stationary. 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.

Ball bearings in electric motors support and locate the rotor keep the air gap small and consistent and transfer loads from the shaft to the motor frame. 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. 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. The problems isn t just the heat it is the current and the conditions in the bearing that would lead to an arc from ball or roller to the race what we are talking about is small arc strikes on the surface that become much harder than the race or bearing and as it rolls around it causes damage that then destroys the other parts.

In extreme cases damage may occur very rapidly. The damage usually appears on the surface of rings and rolling elements and is similar to that produced by electric arc welding. The extent of damage to bearings depends upon the amount of energy and its duration.