I think you're on solid ground, and I do have advanced degrees in engineering. Sorry about the QRT situation.Another point.
I'm not sure why it is so "shocking" to consider that a coil, choke, or transformer in a circuit, at some point in an AC cycle, is seen at the supply as (in essence) a short.
Maybe my ability to describe those conditions is lacking. I'm not an engineer or physics professor. I think in more "animated" or graphic terms.
I also do not follow, precisely, how voltage and current being out of phase equals no power.
Just because they aren't in phase, this doesn't mean they aren't still "there" and calculable, right? I mean if a voltage of y exists in x circuit, and a current of z exists in x circuit, then ohms law still applies (P=ExI), no matter what point in time they occur, correct? Wouldn't this be because in AC, we talk of AVERAGE current and AVERAGE voltage, not peak...right?
Maybe I'm missing something, but I am here to learn.
I think of a dead short, which in actuality is never a perfect short as all conductors have resistance...but this is true whether AC or DC....As minimal as the resistance is, when the current has spiked and all those electrons are bursting through the seams to get through, if I measured the voltage across the short with a meter, would it not be close to zero and out of phase with the current? Yet, nobody can argue that there is no power there. There might even be a small fire!
Voltage is potential, or electrical pressure...and when there is a short, it is no longer potential but rather an occurance whose potential has been released.
I think of a cylinder of compressed air with a pressure gauge and a valve. I open the valve a little, there is flow. There is still some potential because there is resistance in the valve. As I open it, that potential is exchanged for increased flow. The pressure drops a bit at the gauge. If my valve had a large enough oriface to create a large enough flow, I might see the needle on the gauge drop to near zero lbs of pressure, depending on what the supply pressure was to begin with.
Maybe I think in too simple terms for this hobby
OK to be honest since this seems complex. I have a secondary coil only to consider. it is in direct short. The magnetic field from the primary is generating the voltage and thus amperage in the secondary. I don't reall care or am concerned with the voltage or amperage phase of the primary. All I'm concerned about is the voltage and amperage phase of the secondary. So its really just voltage to amperage thru the secondary coil to consider. Does this help. And I need a formula cause I'm building software to chart the data. I can't use online calculators really since they don't plug into the program. I need formulas. And thanks for your guys help, I'm a little confused at this point.
How is the amperage affected? Isn't it limited by the inductive reactance only?
I think you're on solid ground, and I do have advanced degrees in engineering. Sorry about the QRT situation.
Well maybe congratulations are in order then. '73 and Nice to meet youAh, you looked up my callsign on QRZ
Well, I got remarried and had a baby in the past couple of years and decided to put the equipment in storage to make room for more important things. In a few years I'll be getting a bigger house with a room just for my radios.
It is hard to get you what you seem to want because words are not sufficient to describe the situation. A picture, or a drawing, or a schematic might be helpful. One of the hard things to quantify is the strength of the magnetic field, how the field is changing, and how efficient the coupling is to your coil.
A simulator may or may not be helpful in describing and understanding the situation. Now a coil that is shorted is similar to a small resistor in parallel with an inductor. If that is what you are talking about I'm thinking that it will be mostly uninteresting.
BTW with a small resistance (10 milliohms) across the coil the output voltage and current are quite small but they are still out of phase. This is as true at 60 Hz as at 100KHz.
In an AC circuit there is real power and reactive power. Real power (which transmits actual power) is from the component of current that is in phase with the voltage. Reactive power (which transmits no power) is the current component that is 90 degrees out of phase with the voltage. The real power equals the RMS voltage times the RMS current times the cosine of the phase angle between the voltage and current.I also do not follow, precisely, how voltage and current being out of phase equals no power.
Fantasy? That's getting a little nasty. Advanced degree(s) in engineering don't necessarily make you right (although you apparently think it allows you to disparage other's comments).I have worked with transformers. I have measured them and simulated them and I'm here to tell you that the current and voltage on the secondary of a transformer are most definitely not in phase with each other at least as far as I understand the meaning of that term.
One of them may be in phase with the alternating magnetic field that generated the output on the coil. It is also the case that the output of a generator does not have the current and voltage in phase with each other. If it was possible to get a generator to do that, the whole power factor correction industry would be a solution looking for a problem.
You can continue to insist on any particular fantasy that you like, but you should be mindful of the damage you are doing to people trying to learn.
In an AC circuit there is real power and reactive power. Real power (which transmits actual power) is from the component of current that is in phase with the voltage. Reactive power (which transmits no power) is the current component that is 90 degrees out of phase with the voltage. The real power equals the RMS voltage times the RMS current times the cosine of the phase angle between the voltage and current.
A phase angle of 90 degrees occurs when driving a pure inductive or pure capacitive load. A pure inductor or capacitor dissipates no real power, only reactive power. You can thus see how you can have current and voltage with no real power.
The power company quantifies the value of real power with Power Factor. The Power Factor varies between 1, when the current is in phase with the voltage, to 0, when the current is 90 degrees out of phase with the voltage. Power companies obviously want to keep the PF as close to one as possible, to minimize useless reactive currents flowing in the power lines.
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.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.
Real power is real power, independent of the application or frequency. You seem to be confusing reactive power with the radiated power from an antenna. Real power is the power that goes out the antenna and is indeed the desirable power. If you have an antenna perfectly matched to the transmission line characteristic impedance driving it, then it will look like a resistance (i.e. the RF current is in phase with the voltage), there is no reactive power, and all the real power is radiated. That is the whole point of tuning the antenna to match the transmission line and minimizing SWR. You only get reactive power if the antenna is mismatched. Reactive power does no work and is generally undesirable.You bring up real vs reactive and seem to imply that "real power" is some way more desireable than reactive power, or more "real", LOL, which is a deceptive word. If all electronic circuits were designed to energize light bulbs, turn a motor, etc, then you might have a point. However, this is not the case thankfully or my cellphone and radio equipment wouldn't work.
In radio, in fact, REACTIVE power is the desireable power and "real power" is what we seek to mitigate.
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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.
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