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Pf Not Be Unity


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#1 toubar

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Posted 14 October 2009 - 10:32 PM

Hi all,

I have a very small quistion:
Why it's not prefered to make the PF equals unity.

That's all thanks




#2 AB2005

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Posted 15 October 2009 - 05:14 AM

QUOTE (toubar @ Oct 15 2009, 03:32 AM) <{POST_SNAPBACK}>
Hi all,

I have a very small quistion
f33
:
Why it's not prefered to make the PF equals unity.

That's all thanks


Hello,
Welcome to the forum. This question has been asked many times and eng given their answers. I would suggest to "Search" this topic in this forum and you would find many topics.


Best Regards

"Don't assume any thing, always check/ask and clear yourself".

#3 marke

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Posted 15 October 2009 - 05:42 PM

Hello toubar

Welcome to the forum.

There are two major types of displacement power factor correction, static correction and bulk correction.
It is imperative that with static correction, you do not correct to unity because at unity, the inductive reactance of the load is equal to the capacitive reactance of the capacitors and this means the circuit is at resonance at the supply frequency. If the supply becomes disconnected and the capacitor(s) remains connected to the motor terminals, there will be a high voltage generated that will cause major damage. see http://www.LMPhotonics.com/pwrfact.htm
With bulk correction, this is not a problem, but it is difficult to maintain unity exactly.
The normal standard is to be better than 0.95 and this is much easier to achieve and there is very little loss relative to unity.

Best regards,
Mark.

#4 toubar

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Posted 16 October 2009 - 12:52 PM

thanks alot for your concern and for the helpfull inforation

#5 toubar

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Posted 16 October 2009 - 01:01 PM

I'm sorry butihave another quistion in the same topic

what is the advantage from using both bulk and static PFC at the time in the same factory

if it's a duplicated quistion please refer to the place of the answer

thanks,
toubar






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