TACHOMETER The SKF Electrical Discharge Detector Pen (EDD Pen) is a simple to use hand-held 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 programme, the EDD Pen can help detect bearings more susceptible to failure, and significantly prevent unplanned machine downtime. Specifications General Specification Power supply    4,5V – 3 x standard AAA batteries (LR03, AM4) Time control    pre-sets    10 or 30 seconds default    indefinite Operational and storage temperature    0º to 50 °C (32 to 122 ºF) -20 to 70 °C (-4 to 158 ºF) IP level    IP 55 Display    LCD counter range: 0 to 99 999 discharges. User selectable backlight and low battery warning Case Dimensions (w x d x h)    255 x 210 x 60mm (10 x 8.3 x 2.3 in.) Total case and contents weight    0,4 kg (0.88 lb)