Reactive power - Reactive Generator research from GotoLuc - discussion thread

[gotoluc]

Luc, isn't your watt meter plugged into the output of your generator?

Never mind. I see that it is plugged into the AC feed to the genset, which is feeding your motor.

I meant the Watt meter that is plugged in to your generator, not your DMM meters.

Okay, I now understand!... I modified the gen panel plugs, one is connected to grid (with plug in watt meter) and the other plug is the gen output.

Luc

[poynt99]

Would it not be just as easy for me to download it then for you to upload it to a fileshare place?

So not sure what to answer on this one.

Luc

Sure.

You'll have to register with them. Your choice.

[gotoluc]

OK Luc,

I've figured out a big part of the puzzle.

Thank you for showing the channel settings on your scope. When I changed the coupling on both channels to "AC" on my scope, I got the negative MEAN value. I of course have been using "DC" coupling, and you need to also.

The reason that we can't use AC coupling is because doing so inserts a capacitor in series with the probe input. The capacitor is not large enough in value to pass 60Hz without altering it, and it is this alteration (change in wave shape) that is causing your negative MEAN value.

Even if I only change the CH2 probe back and forth from AC to DC coupling, the MEAN value will change from +2.5W to -2.5W. You can see a slight change in the CH2 wave form shape when changing back and forth.

See the attached for a bit of info. With square waves, you can see how much it changes the wave shape, even at 80Hz. We are not using square waves, but the CSR wave form does contain many higher frequencies than 60Hz.

Try changing both channels to "DC" coupling. I think you might see a significant difference in your results.

Now, I still have to figure out why your scope is not displaying the same MEAN value regardless if CH2 is inverted or not (only the polarity should change). They should be the same, and I have confirmed this again with my measurement. The fact that yours changes tells me that there is some sort of offset somewhere that is causing an imbalance so to speak.

Okay, something new learned!... DC coupling when wanting accurate math results from an AC source.
Not a problem. I will do that from tomorrow on.

Thanks for finding that one.

Luc

[gotoluc]

Sure.

You'll have to register with them. Your choice.

Well, if you're ready to upload it to some file share then I'll take you up on the offer. It would be easier then to register and all.

Thanks for your help.

Luc

[poynt99]

Okay, something new learned!... DC coupling when wanting accurate math results from an AC source.
Not a problem. I will do that from tomorrow on.

Thanks for finding that one.

Luc

You're welcome.

I had another gander at the CH2 wave form while changing from AC to DC coupling, and not only does the wave shape change a little, the phase shifts a little too.