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Working with some power factor measurement, this article (reference: https://www.se.com/ww/en/faqs/FA212521/) has this interesting bit:

Issue: Understanding and interpreting the sign of a power factor (PF) value.

Resolution

A lagging power factor denotes that on the phasor diagram, the current lags (is behind) the voltage, and a leading power factor denotes that the current leads (is ahead) the voltage. For inductive loads (e.g. induction motors, coils, lamps), the current lags behind the voltage, thus having a lagging power factor. For capacitive loads (Synchronous condensers, capacitor banks) , the current leads the voltage, thus having a leading power factor. The lagging or leading distinction does NOT equate to an positive or negative value. Rather, lagging corresponds to an inductive load, while leading corresponds to a capacitive load. The negative and positive sign that precedes the power factor value displayed is determined by the standard used, that is either the IEEE or IEC standards.

The upshot from the link is:

According to the IEEE convention, the Power Factor sign is solely dependent on the nature of the load (that is Capacitive or Inductive). In this case, it is independent on the direction of Real Power flow.

For an Inductive load the Power Factor is negative.

For a Capacitive load, the power factor is positive.

Someone mentioned an ANSI standard, but they had the signs reversed (inductive +, capacitive -), but that seems wrong to me.

Is there an ANSI standard, and is the comment mentioned above correct or incorrect?

asylumax
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  • Since Power and Apparent Power are positive, pf is positive. Sign is handled by leading / lagging. – StainlessSteelRat Nov 10 '22 at 22:29
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    Check the ANSI standards. – Solar Mike Nov 11 '22 at 06:59
  • Just heard from a company that does this stuff, and they tell me that yes, the sign convention of ANSI is different than that of IEEE; " the ANSI PF sign convention is “+” for inductive loads and “-“ for capacitive loads." – asylumax Nov 11 '22 at 19:54
  • The very fact that there are three standards makes me think of the quip, “The good thing about standards is that there are so many to choose from.” – asylumax Nov 11 '22 at 20:06
  • Would be curious to know what ANSI standard they're talking about. – LShaver Nov 13 '22 at 01:48
  • Yeah, trying to track this down and get an answer from the manufacturer. It is odd. – asylumax Nov 14 '22 at 03:25

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