Wrong. Consider physics behind operation of an eletromechanical relay or an electromagnet: magnetic energy i.e reactive energy is converted to active power here.
THE PHYSICS OF... POWER
- Thread starter Phil Corso
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Well, there goes this thread, finally. :lol:
FionaZuppa
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Phil Corso
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Energy conservation law (in part): Energy in one form can be converted to another. So reactive energy no exception.
Carultch
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a capacitive motor ?? or the labels were switched?
My mistake. I intended to subtract the phase offset when making the current graph, rather than add it. You will still get the same power curve, just with a different position in time, if you made this for an inductive motor.
FionaZuppa
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your hands at the wheel of search :thumbsup:
FionaZuppa
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I give up..........
Experiment with a 3 phase power factor meter. What results you get?
Phil Corso
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were you looking for the R term related to slip
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Fiona,
Right model, wrong Zeq! Zeq = Z1+Zo || [(R'2/s) +jX'2].
Phil
Fulthrotl
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i can hardly wait. this one paragraph "cliff's notes"
on power has gone *so* well.....
Why? His "Req" represents Thevenin equivalent impedance?
mike_kilroy
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May help also to just write down the bottom line: that triangle again: current into the motor, I, is simply the vector sum of Isq+Isd
WHERE:
- I is what a clamp on ammeter will read
- Isq is the in phase torque producing current (developed due to that slip term that was so MIA until now)
- Isd is the 90 degree out of phase current making the magnetic field, what is the A term referred a lot here as KVARs, this is constant and does not change (simplified comment - you do not need to get into the slight changes due to interactions to other things in the complex model; for these discusions you can say it is totally constant and never changes)
mike_kilroy
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Why would you write such a thing? Are you not an engineer?
Quite simple really: r2/s is NOT equal to Zo||(r2/s)
VERY VERY VERY DIFFERENT VALUES! If you had a clue what these two terms actual values loaded and unloaded were you would not have questioned the correction. Please look it up so you learn the major difference in values.
the reactive energy is not 'converted'
the real power moves the armature
think of it as a simple linear motor
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The real power moving armature is derived from magnetic field energy which ,before movement ,is purely reactive energy.
the power is complex
you have P and Q components
before and after it moves
you don't have all Q before it moves, then all P after
the Q is constant like a motor and the P increases with movement, but the Q does not disappear or get 'converted'
like a transformer or motor you have a var inrush and then real power to operate or generate torque
if it required var a DC relay would not operate
if it were var the meter would not spin with a rack of relays connected
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