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how to measure pf of three phase


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#1 kuldeep

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Posted 23 September 2005 - 06:13 PM

hi all,
i am new member of this forum,i want to improve the power factor of our factory load which is around 100kw,there are different types of mahines running on sigle phase,two phase,three phase,now if i have to improve power factor of our factory by switching capacitor on three phase tell me how to switch it on line.

to find value of capacitor to be switched on each phase should i calculate power factor of each phase with respect to neutral and switch capacitor accordingly.

i have seen some pf corrector in market,what they are calculating pf by taking phase to phase voltage refrence and current of third phase and switch capacitor on all three phases although even load running in factory is on single phase only

thanks
kuldeep

#2 marke

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Posted 23 September 2005 - 08:51 PM

Hello kuldeep

Welcome to the forum.
First I would suggest that you read the web page on PF correction at http://www.LMPhotonics.com/pwrfact.htm
There are two ways of applying correction, you can static correct each machine, or you can bulk correct the supply.

Best regards,

#3 kuldeep

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Posted 24 September 2005 - 05:35 AM

hi marke,
thanks for your reply,i want to bulk correct my supply only point of confusion is wheater i have to switch capacitor on three phase equally or i have to switch capacitor on each phase independently.
the method used for power factor correction by market available pf controller is zero crossing method,the reference of voltage zero is taken from phase to phase voltage of any two phases and reference of current zero crossing is taken from third phase now depending upon lead and lag controller switch capacitor on all three phases equally,is it right method t improve power factor when load is only on one or two phases in factory.

thanks
kuldeep

#4 marke

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Posted 24 September 2005 - 06:19 AM

Hello kuldeep

It is usual to correct all three phases equally. If you have a major imbalance, I would try to improve that by applying static correction to the individual loads that are contributing to the imbalance. This should result in a more balance load at the point of supply.

Best regards,

#5 Guest__*

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Posted 07 October 2005 - 09:59 AM

DEAR SIR ,WHAT ARE ALL THE RULES SHOULD BE FOLLOWED , WHILE CALCULATING PF CORRECTION, FOR EXAMPLE POWER FACTOR CONTROLLER,AND CT, CT DESTANCE CLASS ACCURACY METHOD OF CAPACITOR CALCULATIONS, AND PROTECTION OF CAPACITORS,

REGARDS,.
GGRR

#6 marke

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Posted 07 October 2005 - 07:34 PM

Hello ggrr

The best way to find this information, is from the manufacturers of the equipment.
You will get a good background from http://www.LMPhotonics.com/pwrfact.htm
If you have specific questions, ask them here and we will answer as well as we can.
Best regards




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