induction motor power factor more than one

Don Kelly wrote:


Don, what you're describing here is the 'sign' of the reactive load (VAR). Var load is 'generated' and supplied to loads. But the power factor (cos(theta) or W/VA) is positive for both lagging or leading load (positive or negative VAR load).
If one looks at the trigonometry of it, a 'negative power factor' would mean that you have a negative W (since VA can never be negative) and that would be power reversal (load becomes source).
daestrom
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Thanks, Salmon Egg caught me and I realize the error that I made and wrote lagging pf rather than lagging reactive as positive. The only excuses that I can offer are: I am a lousy proofreader -true. I had too much wine-also true.
I blew it.
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wrote:

SHAME SHAME. I NEVER make a blunder or a tipo. Bythe way, I have a sure investment with a 300% per annum return. Send me your account information so I can add you to my client list.
Bill
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------------------------- tipo?
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Don Kelly snipped-for-privacy@shawcross.ca
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Don Kelly wrote:

That is a tiny typo. ;-)
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------------------- piti! :)
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Don Kelly snipped-for-privacy@shawcross.ca
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Don Kelly wrote:

Well, you asked the question. ;-)
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Another question, can I use your definition of tipo when I play "Balderdash" with my grandchildren? ;)
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Don Kelly wrote:

Try it, and see if they let you get away with it. ;)
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wrote:

--------- The load on the motor plus losses determines the power drawn. The above seems to imply that you can shove power from the system into the motor to get work done- you can't. The supply simply tries to satisfy the needs of the motor and load. -------------

-------- You do this at any power factor. Note that the power of concern is average power per cycle. That is what a wattmeter measures. This should not be confused with instantaneous power (which can be negative during part of the cycle if the power factor is not unity). Reactive power, KVA and pf are also based on average values as is rms voltage and current (which don't actually exist) specific averages. Unity pf simply means that there is no "reactive" load. --------

---------- This is not true. The sign of the "real" or average power depends on whether the machine is generating or motoring but the sign of the power factor depends on the direction of the "reactive power" which is not determined by the direction of the real power. An induction machine whether motoring or generating, will have a lagging power factor, sucking vars from the source. A synchronous motor can have its pf changed from + to - by excitation control without any change in the magnitude or direction of the power delivered to the load. Similarly, it can feed power to the system with independent control of the power and the power factor. By North American convention (British too, I believe), lagging pf is considered +ve. Leading pf is -ve. European convention is the opposite.
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Don Kelly snipped-for-privacy@shawcross.ca
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On Jul 10, 2:41pm, snipped-for-privacy@ipal.net wrote:

no need. thx for making the effort though. It was intended as a slightly sarcastic rhetorical question. perfect reactance theoretically has 0pf. And the power is developed at the generator (or in fact converted). it is dissipated at the load.
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and anyway i am not the OP who posed the question
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