Unable to apply desired load with dynamometer

Discussion in 'Homework Help' started by JackD2, Sep 23, 2012.

  1. JackD2

    Thread Starter New Member

    Sep 15, 2012
    We performed a test of different speed control methods for three-phase induction motors. I believe that another member posted about this exact experiment last year since the instructions look the same (http://forum.allaboutcircuits.com/showthread.php?t=60211)

    In the variable stator supply voltage experiment we had a cage motor connected Delta connected and were able to apply the desired 10N load via a dynamometer in cumulatively compounded configuration. However, when we connected the motor in star configuration we were unable to apply the desired 10N load.

    Basically at the starting voltage of 415V, we were able to apply about 9.75 N, but at each successively lower voltage, the full load could not be applied. When the voltage decreased to 210V less than 1 N could be applied.

    When I say the load couldn't be applied I mean that we turned the load control to maximum and set the shunt field excitation to maximum, but the load couldn't be increased to the desired level.

    I'm not sure why this would be the case?
    Last edited: Sep 23, 2012