power factor Re: control panel measurments

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: dave pierson <davep-at-quik-dot-com> 


>>Thanx for the input.
>>It rings a bell from my electronics school days but I seem to have lost
>>most of it.
>>
>>Out of curiosity if the load seen by the source were purely inductive
>>and the pf was zero can the inductive load do any work?  Like say it
>>were a motor or .............
    Needs to be looked a little deeper.
    A motor (or a transformer) LOOKS like an inductor:
     wires in coils, core.

    In the real world the _impedance_ presented (in each case)
    depends on the load.

    If the load on a transformer is resistive (Tesla coils usually 
aren't.  8)>>)
    THE LOAD SEEN FROM THE INPUT TERMINALS IS LARGELY
    RESISTIVE (low power factor).

    Similarly for the motor case.  A motor running unloaded has
    high inductive power factor.  As the load is increased, the
    power factor shifts towards resisitive.  This is not much
    of an issue for 'common' fractional HP motors.  When motors
    get into the manys of HP it is important and engineered for.

>>Seems that if the true power were zero then there would be no power to
>>be put to work.


>Exactly true... reactive power can do no "real work"

    True.  cf as above.

    best
     dwp