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Power Factor Correction of single phase motors

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#1 Itos


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Posted 25 June 2002 - 08:21 AM

Greetings Mark,

I wasn't able to buy any clip-on power factor meter but did buy a digital clamp amp-meter. Based on your electrical calculations for static correction, all I need to do is supply the amp reading of the motor in order to calculate the kvar. Is it applicable for both single and 3 phase motors?

Thank you in advance.


[Edited on 26/6/02 by marke]

#2 marke


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Posted 26 June 2002 - 08:56 PM

I believe that with a single phase motor, the only real way to determine the required power factor correction will be to measure the power factor and KW (or current) and then calculate the capacitance required to correct it.
Single phase motors often have capacitors already in circuit, depending on the type of single phase motor that it is. Additionally, single phase motors are rather inefficient, having much higher iron and copper loss than a larger three phase motor, so the open shaft current is not primarily magnetising current, but can include signficant amounts of capacitor current and loss currents.
You may get enough data from the motor data sheets if you can locate them.

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