The SKF electrical discharge detector pen (EDD Pen) is a simple to use handheld instrument for detecting electrical discharges in electric motor bearings. Electrical discharges are a result of motor shaft voltages discharging to earth through the bearing, causing electrical erosion, lubricant degradation and ultimately bearing failure. Electric motors are more vulnerable to suffer electrical erosion in bearings when controlled by a variable frequency drive. - When incorporated into a predictive maintenance programmed, the EDD pen can help detect bearings more susceptible to failure and significantly prevent unplanned machine downtime.