Insulated
|
Two Options to Prevent Electrical Pitting Damage
Electrical pitting often occurs in bearings used in electrical equipment, such as motors and power generators, as a result of current leakage. An electrical current present near a bearing can flow to the inside of the bearing, causing sparks that damage the rolling contact surface, ultimately leading to bearing failure. This electrical pitting and can be prevented with coated bearings or ceramic hybrid bearings.
Coated Bearings
NTN’s MEGAOHM™ Series of insulated bearings has been specifically designed to counteract electrical pitting. These bearings are available in both ceramic and resin versions that are suited to a variety of applications. Coating the outer ring of the bearing provides a barrier (capable of resisting at least 100 M? at 500 VDC) against any stray currents that would pass through the bearing.
MEGAOHM™ Series bearings are featured as OEM equipment on wind turbine generators, traction motors for railway cars, and variable speed electric motors in wastewater treatment facilities.
Ceramic Hybrid Bearings
For especially problematic applications, NTN offers ceramic hybrid bearings. Using conventional steel inner and outer rings, silicon nitride rolling elements provide excellent electrical insulation while reducing rotating mass and improving heat dissipation.
The unique properties of ceramic rolling elements can also extend service life and extend grease intervals.
Ceramic hybrid bearings are gaining popularity in the wind energy industry, where service access is difficult and conditions especially harsh.