Hi

I was reading Guru's book on Electric machinery (page 38, 2nd edition) and I stuck here in this:

"The sign of the power factor angle teta can be easily determined from

the type of load. The power factor angle teta must be negative for an inductive load (R + jX) and positive for a capacitive load (R - jX)."

Well, Sadiku's book (fundamentals of electric circuits) tells the opposite...

So when the current leads the voltage then we have θI>θV, which of course implies that the argument of the cosine function, θV−θI, is negative.... (leading pf is seen for capacitive loads...) So the power factor angle for capacitive load should be NEGATIVE and not positive as Guru tells...

I wonder why Guru wrote that power factor angle is positive for capacitive load... well I'm seeing this image...

http://oee.nrcan.gc.ca/industrial/equipment/vfd-ref/images/figure-23.jpg (as Sadiku shows in his book) and it is clear that phi (the angle of power factor) is positive for inductive loads , and negative for capacitive loads!

I got confused.. hope you can help to solve this apparent dilemma..

Thanks in advance!

I was reading Guru's book on Electric machinery (page 38, 2nd edition) and I stuck here in this:

"The sign of the power factor angle teta can be easily determined from

the type of load. The power factor angle teta must be negative for an inductive load (R + jX) and positive for a capacitive load (R - jX)."

Well, Sadiku's book (fundamentals of electric circuits) tells the opposite...

So when the current leads the voltage then we have θI>θV, which of course implies that the argument of the cosine function, θV−θI, is negative.... (leading pf is seen for capacitive loads...) So the power factor angle for capacitive load should be NEGATIVE and not positive as Guru tells...

I wonder why Guru wrote that power factor angle is positive for capacitive load... well I'm seeing this image...

http://oee.nrcan.gc.ca/industrial/equipment/vfd-ref/images/figure-23.jpg (as Sadiku shows in his book) and it is clear that phi (the angle of power factor) is positive for inductive loads , and negative for capacitive loads!

I got confused.. hope you can help to solve this apparent dilemma..

Thanks in advance!

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