NKE Austria recently introduced electrically insulated rolling bearings. The special bearings SQ77 feature a built-in electrical insulation, which provides reliable protection against current discharge and the resulting electrical corrosion. Typical applications of electrically insulated rolling bearings are electric motors, generators and other electrical machines. NKE’s electrically insulated bearings are available in three versions: the SQ77 series, with an oxide ceramic insulation layer on the outer ring; the SQ77E series with an insulation layer on the inner ring and the hybrid bearings of the SQ77B series that feature ceramic rolling elements with theoretically infinite insulation resistance. The SQ77 and SQ77E ceramic insulation is applied through plasma-spraying and has a guaranteed dielectric strength of at least 1000 V AC or DC. The bearings with outer ring insulation are available as cylindrical roller bearings and as deep groove ball bearings in various designs, dimension series and radial clearance classes. Compared to conventional bearings, electrically insulated bearings are more reliable in operation in electrical machinery due to their increased protection against electrical corrosion. They are also more cost-effective and reliable than a shaft or housing insulation. The insulated bearings have the same key dimensions and technical properties as conventional bearings and are therefore 100 percent interchangeable.