Variable 3 phase

Discussion in 'General Electronics Chat' started by karas, Jun 30, 2016.

  1. karas

    Thread Starter Active Member

    Sep 8, 2011
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    In variable 3 phase if the phase is zero this mean all in phase ,but if the phase is 5 this mean the phase between one and other is 5 and with the other is 355 ,is this right?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    No comprendi?
    Max.
     
  3. be80be

    Senior Member

    Jul 5, 2008
    431
    57
    There 120 180 and 360 but wouldn't they all be at 5 just ahead by 180 and 360
    [​IMG]
     
  4. Techno Tronix

    Member

    Jan 10, 2015
    140
    10
    Why 355?
     
  5. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    All I can say is if the phase is zero, it's your reference phase. Phase really shouldn't change for 3 phase. Always 120 deg apart. Frequency will change the speed.
     
  6. tcmtech

    Well-Known Member

    Nov 4, 2013
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    1,673
    Sort of true but in reality there can be some degrees of phase shift depending on the loading. Transformers tend to produce a bit of phase lag from primary to secondary as their load changes so given the number of transformers between the central power station generators and the load if there is a lot of inductive load on one phase and less on another there can easily be a 5 - 10+ degrees of phase variation between any two of the three. More so if the local utility company has some level of PF correction online that brings up the low PF of one phase but then also pushes one of the others a bit too high on PF.

    Given that you could have one phase running 5 - 10+ degrees lagging and another running 0 - 5+ degrees leading in reference to the baseline phase timing.
     
  7. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    True in the details. The power company phases could be loaded differently too.
     
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