Knowledge About Electric Insulation Bearings


Bearing insulation is to use a special spraying technology to spray an insulating coating on the outer ring or inner ring of the bearing. This kind of bearing is an insulated bearing.


Electric motors, generators and associated equipment are at risk when an electric current passes through their bearings. This can damage the contact surfaces of rolling elements and raceways in the bearings (electrical erosion) and rapidly degrade the grease. Another additional risk in electric motors and generators comes from high frequency currents caused by the inherent stray capacitance. The risk of damage increases where the application uses a frequency converter.


CNB electric insulation bearings are designed to prevent electric current from passing through the bearing. The external surfaces of either their inner or outer ring are coated with an insulating aluminium oxide layer, by applying a sophisticated plasma-spray process for an outstanding quality finish. Our solutions are cost-effective compared with other insulation methods.


CNB can supply 500-3000V DC coated insulated bearings according to customer requirements.


The most common international suffix codes for insulated bearings are: VL0241, VL2071, VA3091, J20A, J20AA, J20B,J20C, SQ77, SQ77E, etc. Among them VL0241, VA3091, J20AA, J20A, J20B, SQ77, V3031A are outer ring insulated bearings, VL2071, J20C, SQ77E, V3031B are inner ring insulated bearings.


VL0241, VA3091 means SKF(INSOCOAT) outer ring bearing with insulating coating.

J20AA, J20A, J20B indicate FAG brand outer ring bearing with insulating coating.

SQ77 means NKE outer ring bearing with insulating coating

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