Reactive power - Reactive Generator research from GotoLuc - discussion thread

[gotoluc]

I tried it and it stopped and displays "self calibration failed at step 3"

I'll try it without my 100x probe

Luc

[gotoluc]

Here are the shots with the factory 10x probe on channel 1. Looks to me about the same offset as using the 100x probe!  so I guess it's not the probe causing the offset.

The load is my 10 Ohm 1% 50w Resistor with 10 volts RMS across it = 10 watts
I also took the opportunity to make my own precision CSR (shunt resistor) out of Resistive wire which makes 0.1 Ohm with about 2 1/8" inch of wire. Now I have a precise CSR which also should more reliable then a wire wound CSR.

I think this should be precise enough to get back to testing. What do you think?

Luc

[poynt99]

Here are the shots with the factory 10x probe on channel 1. Looks to me about the same offset as using the 100x probe!  so I guess it's not the probe causing the offset.

I suspected the current probe might be the problem, not the 100x voltage probe.

The load is my 10 Ohm 1% 50w Resistor with 10 volts RMS across it = 10 watts
I also took the opportunity to make my own precision CSR (shunt resistor) out of Resistive wire which makes 0.1 Ohm with about 2 1/8" inch of wire. Now I have a precise CSR which also should more reliable then a wire wound CSR.

I think this should be precise enough to get back to testing. What do you think?

Luc

The only potential issue with the nichrome wire idea, is that the value may change quite a bit if it warms up. I guess you will have to try it and see.

Your MEAN values seem a little closer to one another now...within 2%, so perhaps that is acceptable for what we are doing here.

Unless I find something else, I see no reason that you can't go back and start remeasuring the tests you wish to remeasure for comparison. I for one would like to see you remeasure the simple cap and resistor load circuit.

I would caution however, that it would be a good idea to check the MEAN power with CH2 both inverted and non-inverted. If there is a big discrepancy between the two, then we should try to figure out why. And remember to get about 10 MATH cycles (5 Voltage cycles) on the display for the measurement (you have 12 in your scope shot above, and that is perfect).

[gotoluc]

I suspected the current probe might be the problem, not the 100x voltage probe.

I have 3 other factory probes, I can try them but quite sure I keep rotating them, so I don't think the probe is the problem. I also do probe comp check quite often.

The only potential issue with the nichrome wire idea, is that the value may change quite a bit if it warms up. I guess you will have to try it and see.

Very good point!... I'll make sure to use it only on small loads that don't heat the wire. Anyways, I'm only interested in circuits that don't use much power.

I for one would like to see you remeasure the simple cap and resistor load circuit.

Well, I quite sure you know the results!... It should be under unity with probes set to DC coupling. One very valuable lesson learned there. Too bad it took so many pages to figure it out. Also found out many others were doing the same thing.

I would caution however, that it would be a good idea to check the MEAN power with CH2 both inverted and non-inverted. If there is a big discrepancy between the two, then we should try to figure out why. And remember to get about 10 MATH cycles (5 Voltage cycles) on the display for the measurement (you have 12 in your scope shot above, and that is perfect).

Yes, I've got that also and now understand your reasoning  to use invert as a way to check for potential problems.

Thanks for your help and I do hope you will put up a YouTube video Tutorial to help other researcher with this needed information as I've checked a while back on YouTube and there is nothing on how to use a scope for power calculations.

Luc

[poynt99]

Luc.

Thank you.

I sincerely hope there was more than one lesson learned here by all. I certainly learned a few things.

And yes, I still hope to get your buy-in to the CH2 inversion requirement when making power measurements where polarity is an issue (like when claims of OU are involved). My video will hopefully explain clearly why the inversion is required.

So unless there is something you or anyone else would like to see with my setup, I guess this will be the only video I need to make (perhaps a short series of vids is appropriate) . Do let me know.

.99