# Reactive Power Absorption

Discussion in 'Homework Help' started by Stereoblind, May 15, 2015.

1. ### Stereoblind Thread Starter New Member

Mar 10, 2015
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Hey guys,

I'm having a few issues understanding the following statement:

"A capacitor bank generates lagging VArs and absorbs leading VArs".

My understanding is that if we have a lagging power factor our current is behind our voltage, indicating an inductive load. So surely a capacitive bank would absorb lagging VArs since the leading/lagging relationship has been flipped?

Apologies if this is a dumb question but I just can't get my head around it for some reason. We have a similar section relating to generators and it's confusing me :/ .

2. ### Dodgydave Distinguished Member

Jun 22, 2012
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744
use the Mnomenic CIVIL

capacitor current leads the voltage ,

Last edited: May 16, 2015
3. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
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Where did you read that statement? Hopefully you didn't hear it from your professor.
Your doubts are well founded and your proposed ammendment to the statement is correct.

4. ### WBahn Moderator

Mar 31, 2012
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By your own description, an inductive load has a lagging power factor when it is absorbing power, so wouldn't it be reasonable to say that an inductor absorbs lagging VARs?

5. ### crutschow Expert

Mar 14, 2008
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3,227
I would say (and I think the convention is that) an inductor generates lagging VARs and absorbs leading VARs, the opposite of a capacitor.

6. ### WBahn Moderator

Mar 31, 2012
17,716
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I have a feeling that it's a matter of terminology and that I may well have it mixed up.

I think of "generating" and "absorbing" in terms of power and energy transfer and from that perspective both an inductor and a capacitor "absorb" reactive energy though that is a poor description since they are constantly absorbing it and releasing it and the phase relationship is constant for either case. None-the-less, from that perspective, if you are going to use a phrase saying that it is either absorbing or generating VARs, associate absorption with the phase relationship that it operates at. But it has been a while since I've been exposed to this terminology and I think, thanks to your response, that the mindset leading to the conventional terminology is weird and comes from a weak and superficial analogy in that if you have an inductor, in which the voltage is leading the current (so a lagging power factor since voltage is used as the reference), that the inductor is somehow "generating" the lagging VARs associated with that situation. That seems like a bass-ackwards way of looking at the concept of power generation, but from the perspective of someone managing power factors is probably not too unreasonable and is probably quite useful.

So I agree with you and t_n_k.

7. ### Stereoblind Thread Starter New Member

Mar 10, 2015
14
0
It's in the notes beside an example. Thanks guys, my head was scrambled trying to understand what was going on.

8. ### crutschow Expert

Mar 14, 2008
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3,227
I think the terms "absorb" and "generate" make more sense when used in relation to the VARs involved, and not considering the energy flow.
Thus a logical definition is that the VARs that get larger with a larger inductor means the inductor is generating them and the VARs that get smaller with a larger inductor are being absorbed.