I'm not sure that post helped the OP either. He just wants to know how to measure the power-factor out of a coil being induced by a magnetic field.

dev, easiest would be to measure the peaks of both current and voltage, then calculate how much time they are out of sink.

if time == 0 then they are in phase == 1.0 PF
if time == 1/4 freq period then they are 90degrees out of phase == 0.0 PF.
Just interpolate the rest based on the wave form.

smanches,

I currently can't measure the peaks as I have no oscilliscope at the moment. I will buy one eventually, but for now I'm out of luck, I can only calculate. And that is what I must do I guess. Although I would love to get my hands on an oscilliscope, I think I soon will.

I'm really interested in formulas for calculating phase, I'll look at the PDF now and see if I can use something in there.

Guys, I calculated the inductive reactance earlier and used it to calculate the amperage at different points, is that the correct way to do it? I got in phase amperage and voltage, which makes me think its incorrect since I calculated it at 6khz which everyone seems to agree is out of phase.

ke5frf,

I got into the PDF and noticed that I can get the phase angle from the reactive inductance of the coil. Basically theta equals the arctan of the reactive inductance.

So my question is this: does my value for the reactive inductance change at different points along the voltage wave, or is it a constant value throughout the wave?

I think that may be the answer I'm looking for. Thanks.

devronious,

Glad the pdf helped...I didn't write it, just Googled it.

There is a point with all the math and trigonometry where my brain starts turning to mush and the concepts begin to confuse me. Probably why I'm not an engineer.

So I will defer explaining the math to someone more qualified.

And I certainly HOPE that some of the things I mentioned helped reinforce your understanding of the theory. In fact, I would appreciate feedback about that. The Cebik webiste I linked to, if you are so inclined, will open your eyes in a lot of ways. If you get time I highly encourage some reading.

Good luck with digging into all the math and modelling this with software.

Originally Posted by Papabravo

As I read the original question it was not about measurement, but a theoretical query about weather in an inductor with some parallel resistance is it possible to have the current and voltage in phase giving a power factor of 1. My answer is that it is not. We have a difference of opinion which can be settled by either a coherent theoretical proof or by experiment. However, even in the face of overwhelming evidence some people will remain unconvinced. This appears to be such a case, and thus it is pointless to continue this thread.

Although he said when being induced by a magnetic field. This is the difference that makes it have a PF of 1.

OK, I am comfortable with being incorrect with some terms and some concepts. I do not wish to contribute to any confusion. It has, admittedly, been a while since I studied or applied much of this stuff, and...use it or lose it so to speak.

I do feel like I've mixed up a thing or two in my own mind so I'm going to dig out some books and read.

I'm digging into it all right now too. There is almost no information about the phase relationship on the output windings of transformers.

I'm just going to have to setup the experiment at home tonight, since simulation does not seem to satisfy everyone.

OK, perhaps this is where I am wrong or misunderstand...Or perhaps I am right or half-right. Whatever.

RADIATION OF ELECTROMAGNETIC ENERGY

I know this thread is about coils and transformers, but it has always been my understanding that AC theory is the same "forest" despite differences in the "trees", so that is why I keep going back to RF transmission and antennas.

On the page I linked, it states this:

4-6 1. A current flows in the antenna with an amplitude that varies with the generator voltage. 2. A sinusoidal distribution of charge exists on the antenna. Every 1/2 cycle, the charges reverse polarity. 3. The sinusoidal variation in charge magnitude lags the sinusoidal variation in current by 1/4 cycle.

A 1/4 cycle is 90 degrees out of phase.

At the top of the page, if you click "previous page", (not the windows icon, but rather the link provided on the page) you see the same depiction from the Cebik site showing current and voltage distribution, 90 degrees out of phase.

I have always concluded that in a properly tuned antenna system that voltage and current where not in phase.

Yet in doing a little reading of other webpages I'm getting some contradictions.
So it definately looks like reading an actual BOOK instead of the internet, to refresh, is in order LOL.

Yes, that would look correct if you are sending a signal through an inductor. But didn't you mention that you are supplying the magnetism itself to induce the current/voltage?

Originally Posted by crutschow

I believe the confusion is the phrase "variation in charge magnitude lags the variation in current". It does not say the variation in current lags the voltage. The variation in current is in phase with the voltage, but out of phase with the variation in charge. Make sense?

Also again regarding a generator, transformer or any induced voltage in a coil: Smanches is correct. The voltage is in phase with the magnetic change. Any phase shift at the output is due to the reactive charactistics of the load. It is not due to any inherent inductance of the transformer/coil/generator (ignoring stray or parasitic inductance).

No, I don't think there is confusion.

Further reading from the same article:

Figure 4-6.—Standing waves of voltage and current on an antenna

"Look at the current and voltage (charge) distribution on the antenna in figure 4-6. A maximum movement of electrons is in the center of the antenna at all times; therefore, the center of the antenna is at a low impedance. This condition is called a STANDING WAVE of current. The points of high current and high voltage are known as current and voltage LOOPS. The points of minimum current and minimum voltage are known as current and voltage NODES."

And if you refer the diagrams, the point of high current "loop" is at the place where voltage is zero, or the voltage "node", and where current is zero, there is a voltage loop...and the voltage loop corresponds to areas of high charge magnitude.

I realize that voltage and charge are two different things, but that doesn't mean they aren't related, or rather aren't UNRELATED.