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Participant

Join Date: May 2010
Posts: 1

Utility Maintenance

05/17/2010 7:41 AM

i m working with a company, our power factor is going low for few weeks, how can i check capacitor capacity and how much rating capacitor should i install to improve power factor

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Commentator
India - Member - PROFESSIONAL Engineering Fields - Power Engineering - electrical planning - designing

Join Date: Sep 2007
Location: Ahmedbad, Gujarat
Posts: 98
Good Answers: 1
#1

Re: utility maintenance

05/17/2010 8:21 AM

TYPICAL CALULATIONS ARE GIVEN FOR IMPROVING P.F Q1 TO Q2 FOR 567 KW

CAPACITOR SIZING CALCULATION FOR CAPACITOR BANK

Here,

KW=567.00KW
Q1=0.85
Q2=0.91

C

=KW X (TAN (COS

- Q1) - TAN (COS-Q2) )

=567 X TAN (COS - 0.85) - TAN ( COS-0.91) )
=567 X (0.62 - 0.455)
=567 X 0.165
=

93.555

KVAR

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Guru

Join Date: Feb 2009
Location: Houston, USA
Posts: 947
Good Answers: 245
#2
In reply to #1

Re: utility maintenance

05/17/2010 6:54 PM

See this recent thread for detail calculation: http://cr4.globalspec.com/thread/54230/Capacitor-value

- MS

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"All my technical advices in this forum must be consulted with and approved by a local registered professional engineer before implementation" - Mohammed Samad (Linkedin Profile: http://www.linkedin.com/in/msamad)
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Power-User

Join Date: May 2010
Posts: 144
Good Answers: 1
#3

Re: Utility Maintenance

05/18/2010 11:11 AM

From your question, I understand that the problem is started for few weeks only. There were no problem before. So that means your existing design for the selection of capacitor bank is correct. Now, how did you find out that power factor is going less. From the Pf meter?...The solution for your problem is not to add capacitors. But you have to find out the reason for this and rectify it. Investigate the type of load and what are those load when you noticed low power factor. Inspect individually these equipments for example motors, UPS, flouresent lamps etc. If really the initial selection of your capacitor bank is correct, you can find the reason of problem from these equipments. Rectify it.....otherwise ill you add capacitors again, if tomorrow the power factor gone less again??, ( or you just posted for getting information of capacitance selection??

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