Talk:Power factor

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Confusion about Negative Power Factor

I came to this page to try to understand why a power datalogger was giving me a negative power factor. In the page itself, it states that PF can be negative but does not provide any interpretation of this. In the calculation method given, the only way to get a negative PF is if the power flow is in the direction opposite the originally-selected convention (in other words, if you define point A as SOURCE and point B as LOAD and you have power flowing from B to A, then PF is negative). This jives with my understanding of PF but it does not make sense on my datalogger. It turns out that the datalogger uses the convention that negative PF means current lagging the voltage. This makes no sense at all to me, mathematically, and indeed I found a paper online by one of the authors of the IEEE standard on measuring power factor which says that this convention (sign indicating phase shift direction) should not be used as it is confusing.

I think that this subject should be addressed in the article. In other words, it should state that there are various interpretations of negative power factor but that only one interpretation is consistent with the mathematical formula for calculating PF (that is, that negative PF indicates reverse power flow).

I was about to edit the page to add this but then I saw this talk page. All I can tell from the talk page is that there was a huge argument and one person is continually accused of espousing a fringe theory - but I cannot tell what people think is fringe versus mainstream. What is the consensus here about how to interpret negative PF and do you think that should be made explicit in the article?

Thanks Sbreheny (talk) 00:13, 8 April 2014 (UTC)[reply]

Fringe theory: "There is no such thing as a negative power factor"

Obsolete convention: Phase angles (lagging) in the range of -90° to -0° have a negative power factor. Phase angles (leading) in the range of +0° to +90° to have a positive power factor. Phase angles in the range of -90° to -180° and +90° to +180° are undefined. Some meters using the obsolete convention incorrectly show -90° to -180° as having a power factor in the range of -1.0 to -2.0. Some incorrectly "peg the needle" at -1.0. Some display "error". Some incorrectly give the same reading for -45° and -135° (this appears to be the source of the fringe theory). Also, some meters using the obsolete convention display "-" for leading and "+" for lagging.

Alas, the above is from personal experience, and is thus WP:OR. If we could find references, we could add a section on this to the article.

Current, standards-based definition: Phase angles (leading and lagging) in the range of -90° to -0° and +0° to +90° have a positive power factor. Phase angles in the range of -90° to -180° and +180° to +90° have a negative power factor. Power factor readings do not indicate leading or lagging. Modern meters often have a separate display giving the phase angle.

Of course -0° and +0° are the same angle and -180° and +180° are the same angle. One could use 0° to 359.999...° (has anyone ever done this when talking about AC power?) to remove this minor quirk.

There is more on this at http://powerstandards.com/Shymanski/draft.pdf

--Guy Macon (talk) 02:57, 8 April 2014 (UTC)[reply]

Oh My God, some idiot is starting up this debate AGAIN. Better check the archives ([1], [2]), Mario Castelán Castro. Millions have died and lands have been laid waste over this question. --Chetvorno^TALK 00:27, 11 October 2014 (UTC)[reply]

If you see a minus sign when your datalogger is displaying power factor, it means current is flowing the opposite way than expected. Reverse the dot and non-dot connections to each phase CT and the negative sign should go away. Not all instruments behave this way, and I have several amusing pictures of randomly flickering negative signs (and even power factor displays showing values over 1). --Wtshymanski (talk) 21:23, 31 October 2014 (UTC)[reply]

[Big Groan] DieSwartzPunkt (talk) 16:43, 9 November 2014 (UTC)[reply]

Wtshymanski, as it clearly states at the top of this page, this is the talk page for discussing improvements to the Power factor article. This is not a forum for general discussion of the article's subject. --Guy Macon (talk) 19:40, 10 November 2014 (UTC)[reply]

WARNING***WARNING***WE ARE AT DEFCON-3 Please, for the sake of the world, pick up the red phone, stand down the bombers, pull back from the brink before it is too late. --Chetvorno^TALK 02:40, 11 November 2014 (UTC)[reply]

Power

Back in the 1960s when I was a stripling EE undergraduate at IC, London, it was impressed upon us with some force that power is simply power, and needs no qualification (real, imaginary or apparent). To qualify it is to add confusion. The quantity described here as apparent power is simply VA - voltamperes, while so-say "imaginary power" is simply VAR - volt-amperes-reactive. Is this terminology alien to Wiki authors - it seems to be preferable to me.77.96.60.31 (talk) 18:47, 9 January 2015 (UTC)[reply]