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This is the first i have heard 12.47 kV systems being called basic electrician knowledge base. Or did you miss that one?

?-)

What do your designs do when the product of current and voltage are negative?

So how did you get an unsigned PF, did you take the absolute value of current and voltage before multiplying or absolute value of each power before computing the ratio? Or did you use a different trig function?

Rick

thing

laws.

Frequently, but not always.

?-)

But power can be a negative number depending on which way it is flowing, no?

Rick

Ok, if you *insist* in using a non-primary source for your references, here it is from Wikipedia...

The *power factor* of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit,[1][2]

Then here are the *primary* references for that statement...

1. ^ IEEE Std. 100 Authoritative Dictionary of Standards Terms, 7th editionISBN 0-7381-2601-2

1. ^ IEEE Std. 1459-2000 Trial-Use Standard Definitions for the Measurement of Electric Power Quantities Under Sinusoidal, Nonsinusoidal, Balanced, or Unbalanced Conditions, Institute of Electrical and Electronics Engineers Inc., 2000, 0-7381-1963-6. This standard says in Note 1, section 3.1.1.1 when defining the quantities for power factor, that real power only flows to the load and can never be negative

The IEEE is defining power to the load as a positive number ONLY in this calculation. So power factor can not be used in cases where power is flowing *from* the load and therefore can not be negative.

What others do to bastardize the definition of PF is irrelevant. If you want to add a sign to indicate leading or lagging phase, that's fine, but under the definition of the IEEE it is not what they call "power factor".

Rick

Do they mention "leading" or "lagging" ?

Ask me again after trimming your post please...

Rick

How does it work that precludes modification of existing meters?

Such as???

Rick

Yes, standards of voltages is one of the common items on the list that a electrician is suppose to know. 12Kv lines and substations are common in my area. I don't know what you use, guess it does not matter.

Jamie.

If the product is negative, then it is. That happens every cycle in any real system. My meters would report negative power. They wouldn't generally integrate negative power into energy, or very small amounts of power into energy. Some had two energy registers, one for positive integrated power and another for negative.

Negative power sends the message "you have the CT wired backwards"

Unsigned PF is just power/VAs. If you carry the power sign through, the final sign is not equivalent to leading/lagging; it's the PF of the signed power.

To get leading/lagging, you do power/VAs but phase-shift the voltage (or current) waveform 90 degrees, multiply and average, and examine the sign of that.

How one interprets the four quadrants (power +-, PF leading/lagging) isn't universally agreed on. One has to just state ones definitions.

This can be made very complex, when in real life it's just two sine waves with some phase angle between them.

It's amazing sometimes to talk to experienced power and utility engineers. They get confused about this stuff too.

And Thompson has nothing to say on-topic.

How did that startup supply thing work out? Give up?

Definitions are malleable; use the ones you like.

My meters don't measure phase angles. They sample the voltage and current waveforms and compute power as the average of the sample products. That is closer to true power than EIcos(phi), because the waveforms aren't generally sinusoids. EIcos(phi) is literally a simplification and a distortion of reality.

The old "definitions" of power and PF come from the olden days when most everything was (or was presumed to be) a sine wave and electromechanical instruments could only report simple numbers. Life is more complex now, but we have fast ADCs and digital processing to do it right.

Some people call it "leading" and "lagging", and some people use a sign to say the same thing, negative for leading. I don't see why so many people get worked up over a simple and useful sign convention.

Larkin bloviates. Fields feeds his trolling. It's like a neon sign flashing "Larkin, Larkin, Larkin..."

Stop the feeding. Stop the flashing neon sign >:-} ...Jim Thompson

Definitions are just words. If you want to do math, you state your definitions and assumptions, then do the work. A different set of definitions is prefectly valid, if clearly stated and followed for the duration.

Some people use it as such, defined as I've stated. I don't know why you are so upset about this; it probably doesn't even matter to you. You don't do much electronics, but you sure like to agrue about words.

A convention, and a definition, stand on their own. State them, then do the math.

This GE manual presents some optional sign conventions for PF. Pick the one you like, and punch some buttons to have the instrument report that way.

One of their modes agrees with what most of my meters report. As noted, I can also deliver digitized waveforms, so people can call them whatever they like.

It's just words.

How do you define phi for the current waveform like you'd see into an SCR-controlled bridge rectifier?

Really, you can't imagine any scenarios where power would be either positive or negative and both be valid?

So PF can be negative without including the leading lagging indicator?

I'm trying to make it simple, but it seems to get very complex when you reply.

Rick