Reactive power - Reactive Generator research from GotoLuc - discussion thread

[gotoluc]

Despite what Stefan says or your EE friend says, I am correct. I would bet my house on it. If your EE friend would like to discuss it, I would welcome the challenge. This is so basic, it is pitiable that no one will just look at it objectively and let the facts decide.
When you say "circuit uses power" you should be more specific in what you mean. But if you mean everything to the right of the Grid generator, then you would be correct. The power in the dissipative elements, if measured properly is positive. Remember the mantra? Where are your probes for these two scope shots?

So, notice that the power remained essentially the same, but the polarity changed? The only problem is in the understanding of which polarity is the correct one. And since any OU claim hinges on the measured polarity, isn't it important to iron this problem out? If you agree, then please, anyone, explain how the diagrams I posted illustrating the power polarity in sources vs. loads is incorrect, or don't apply here.

Let me ask all here; in the simple diagram attached, is the computed power in VBAT and RLOAD the same polarity or opposite?

A question for Luc: please rearrange the probes in your diagram if you wanted to measure the power in your load resistor that is in series with the primary. Do you expect the power polarity to be the same as that when you measure the Grid power?

Poynt, I would be the last one to say I know more than you when it come to measuring P in & P out.

You ask me to change things, I redo it with your changes then you say something is wrong! I don't understand what you want!

I don't have a problem doing it your way but you need to confirm what is what because everything is now upside down and it's going to take some time to get use to it.
You say channel 2  probe needs to be inverted, fine no problem
So now, what part of the math is the power used and power returned? below the zero line or above it?
You say the only math function needed is mean,  so will a negative mean be more power used or returned or the other way around?
Anything else I need to know to evaluate how much power a circuit is using compared to returning?

Thanks for your time

Luc

[poynt99]

Luc,

I made made a post while I was in the office, but got busy and must have forgotten to hit "Post".

Anyway, I know this must be frustrating for you to a degree, but stick with it. I may be doing a poor job of explaining things, but I am trying my best. Have patience with me please.


If you would be willing, I think it would be very beneficial to go back to the basics for a brief moment. Set up a test like I have depicted in the attached diagram. A simple DC circuit with say a 10V supply, a 100 Ohm resistor load, and a 0.1 Ohm CSR here.

Perform the battery power measurement as shown. Move the CSR and perform the RL power measurement (the load). Note the power polarity of the battery with no inversion on CH2; what polarity is it? Also note the polarity of the RL resistor with no inversion of CH2. Are they the same polarity?

If done correctly, you should get -1W for the battery power with CH2 inverted, and +1W with CH2 not inverted. In addition, you should get +1W for the load power with CH2 inverted, and -1W with CH2 not inverted.

If you obtain these results, then you have proven two things:

1) The power polarity of sources and loads is opposite.
2) The correct power polarity for Sources is negative, and for Loads it is positive.

And we know in order to obtain the correct power polarity, we need to invert one of the scope channels, because in both cases the probes are not placed in series adding, they are placed in series opposing.

This test would only take you 30 minutes or so, and it would be very worthwhile. From here we'd be ready to move on to your test apparatus measurements for which I'd be happy to draw up for you if you wish.

Note: It would be preferable to use a battery for these tests, but you could also gnd isolate your lab supply so that the CSR does not get shorted out for the RL power measurement.

[poynt99]

So now, what part of the math is the power used and power returned? below the zero line or above it?
You say the only math function needed is mean,  so will a negative mean be more power used or returned or the other way around?

Luc, the MATH trace is an instantaneous representation of the power because you are multiplying a voltage by a current. In order to determine if the net average power is positive or negative, we apply an averaging measurement to the trace via the "MEAN" measurement.

When you use "MATH min" or "MATH max", you do not get very much useful information. Why? Because this is only telling us what the lowest or highest peak the trace ever reached on the scale. It doesn't tell us anything about what the over all average power is. So you can not simply add or subtract those two values to obtain the average power. The only way to do it properly is to use the MEAN measurement of the MATH trace. Once we establish what polarity the source (Grid) power is with a simple measurement as I show above WITH the CH2 inverted, the Grid power measurement will tell us if the net average power is returning to the grid, or being dissipated in your circuit. So a proper Grid power measurement that results in a POSITIVE polarity, would mean that more power is being returned to the grid than what your circuit is using.

Anything else I need to know to evaluate how much power a circuit is using compared to returning?

I hope the above answers this question.

[allcanadian]

@dklyne
small world, I use the Arduino Uno then calibrated voltage dividers/opto-isolation for voltage and a pair of 50 or 100 amp Allegro hall effect current sensors. No issues no worries , works every time.


AC

[gotoluc]

Hi Stefan and everyone

I made this video as per Stefan request to see in fine details (scope) the power to the generator prime mover when the circuit is connector or disconnected.

Link to video: http://www.youtube.com/watch?v=0yudbBBSS58&feature=youtu.be

Luc