Motor Load and No Load Amps

Discussion in 'General Electronics Chat' started by ronscircuit, Jul 2, 2012.

  1. ronscircuit

    Thread Starter New Member

    Jul 2, 2012
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    0
    I have a three phase motor that has a range of 575 Vac to 635 Vac. Is the following correct?

    Under a no-load condition, the motor amps will increase with increasing voltage.

    Under a full-load condition, the motor amps will decrease with increasing voltage.

    Thanks,

    Ron
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,001
    745
    NO, motor current increases with load, so more load = more current.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,053
    3,244
    Yes, in general the no-load motor current will increase with voltage due to the magnetizing current, and the (constant) full-load motor current will decrease (assuming the voltage does not go above the rated voltage) since the motor input power remains essentially constant.
     
  4. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    I'll second the yes, within context.

    Decreasing slip, decreases current. At load, slip can be decreased by increasing voltage. This % slip approaches that of no load. Beyond that however, an increase in voltage increases current.
     
  5. WBahn

    Moderator

    Mar 31, 2012
    17,777
    4,805
    I'll third. This is my understanding as well.
     
  6. WBahn

    Moderator

    Mar 31, 2012
    17,777
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    The key to the question is that each question is asking about what happens as the voltage is changed while the load, for that question, is kept constant.
     
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