Full definition
Erosion pattern of parallel grooves (channels) on bearing raceways caused by parasitic electric current passing through the bearing. Primarily occurs in motors with variable frequency drives (VFDs) generating common-mode voltages. Microscopic electric arcs melt and resolidify the steel, creating a washboard-like surface texture. Solutions: insulated bearings (INSOCOAT), insulated coupling or shaft grounding ring. Brands: SKF INSOCOAT, FAG J20AA.