Perske saw motors are high speed motors typically used in woodworking and shaping machines. The motors are usually driven by a rotary frequency changer giving a smooth sine wave supply at high frequency. Our customer had a number of these motors fail due to a problem with the supply voltage when changing from a rotary frequency changer to an inverter. We received the motors in our works and found that they were burnt out. As usual the repair was urgent so our engineers worked throughout the night stripping and winding the stators. We rewound the stator with inverter duty magnet wire that has better protection against high voltage spikes. The insulation class of the rewind was to a full class ‘H’ specification. The rotor was balanced in our high speed balancing machine to G1.0. New bearings were supplied and the motor was run at 100Hz giving an output speed of 5880rpm for this motor.

 Burnt out Perske Motor.