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Synchronous Speed to Shaft Speed

  1. Oct 2, 2016 #1
    Hi All

    I have a standard induction motor torque vs. synchronous speed diagram and I want to calculate the shaft-speed at any point along the curve (from 0% synchronous speed to 100% synchronous speed). I know that the synchronous speed is 1500 rpm at 95% synchronous speed (which is also at full-load), at full-load the induction motor experiences 5% slip.

    Now, I know that the equation nshaft = nsynch*(100-%slip) will give me the shaft speed at full-load, but I also know that the slip changes as per the amount of torque/synchronous speed.

    At 0% synchronous speed there is 100% slip and at 100% synchronous speed there is 0% slip.

    Is there any method to how you can calculate the shaft speeds on the information i've presented? 1500rpm synch speed and 5% slip at full-load.


    Thank you for your help
  2. jcsd
  3. Oct 5, 2016 #2


    User Avatar
    Gold Member

    Yes, I think you can calculate it, at least by numeric methods ( computer simulation ).

    You may find an approximate result, using circle diagrams.

    Try to Google:
    circle diagram of induction motor
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