SurgeTesting a Servo Motor

             When a servo motor comes in for repair, one of the most important tests  is the surge test, which tests the windings to make sure there is not a break or short  in it. 
           A surge test is an impulse test used to determine the diaelectric strength of the interturn insulation turn to turn, phase to phase, in a coil or winding.  It displays up 2 phases at a time so you can compare them.  This is done by using the surge tester and testing all 3 phases of the motor.  While under electrical load, we monitor the wave-form patterns and look for a balanced wave-form on each phase which tells us that it is good.  If the phase is bad, the wave-form is unbalanced and can contain a straight line or an erratic look to it.  In this case, the phase is good.





       










   A comparison of the 2 wave-forms from 2 phases during the surge-test, shorts in one winding will cause a separation in the 2 wave-forms.  There are 3 phase combinations to compare.  If shorts are present, that stator will need to be rewound. 
             In that case, we would send it to our winding department where it will take 2-3 days for completion.  Before we reassemble the motor, a final surge-test is done to complete the repair. If it passes, it is then assembled and a run test follows.  

For more information on servo repair.  Repair Zone has repaired over 12,000 servo motors.