What Capacitance is Needed for a 50 kW Load with a 60% Lagging Power Factor?

[andyskin]

Please can you have a look at the file at point me in the right direction if I'm wrong.

Thank you

 

[anorlunda]

Welcome to PF.

I moved your post to the homework help forum. Normally, we don't allow posts in the form of all pictures in a PDF file, but your pictures are easy to read. I hope you attract some hints from our helpers.

Next time, please type in the text parts of your question and use copy/paste or the ATTACH button to include pictures of the graphics.

 

[andyskin]

Sorry didn’t know there was a homework section

 

[ammarb32]

Hi,

I'm not sure what you're trying to ask in the question. Determine the capacitance that must be placed in parallel to...? What are you trying to do? In the PDF file you attached, it seems as though you're trying to correct the Power Factor from 0.60 to 0.90. However, you're also solving for the Power that needs to be supplied?
Is there a part of the question you might have forgotten to add?

If you're trying to correct the Power Factor from 0.60 to 0.90, please find the Power Factor Correction.pdf file attached. This is the method that should lead you to the correct answer if you want to determine the value of the capacitor required in order to correct the Power Factor.

 

[andyskin]

the full question meant to read:

A 50 kW load operates from a 60 Hz 10 kV rms line with a power factor of 60% lagging. Determine the capacitance that must be placed in parallel with the load to achieve a 90% lagging power factor.

 

[ammarb32]

the full question meant to read:

A 50 kW load operates from a 60 Hz 10 kV rms line with a power factor of 60% lagging. Determine the capacitance that must be placed in parallel with the load to achieve a 90% lagging power factor.

I see. Then, in that case, you just need to change the ending of your method. You need to equate the two equations of "XC" (Finding the reactance that's coming from the capacitor). I attached the derivation of that in the Equations.PNG file. The reason for this is because your "Active Power" (P) is not changing when you change the Power Factor. However, your "Reactive Power" (Q) is changing with the different Power Factors.
Capacitors supply reactive power "Q" to the circuit. Therefore, you need to use the "change in reactive power" to calculate the capacitance value needed to supply that amount of "Q".

 

[andyskin]

thank you for your help, i'll have a look