D
Default User
Hi,
Let's say I start with 120VAC and 2A, both RMS. If I generate samples for
one cycle @ 60hz, I will have voltage samples raning from -169.7V to 169.7V,
and current samples from -2.83A to 2.83A. Let's say I then make the current
lag behind the voltage by 45 degrees, and I multiply the V sample by the A
sample to get a VA sample, I get these three graphs from Excel:
http://home.earthlink.net/~alank2/pf.gif
The top one is voltage, the middle one is amps, and the bottom one is V*A
(watts).
If I average all the samples in the V*A chart, I believe I will get True
Power (watts) from this measurement.
My question is, without the V or A samples, just the V*A samples, can you
calculate the Apparent and Reactive Power?
It seems to me that looking at the graph (bottom one) that there should be a
way, but I can't figure out how to do it.
I was able to calculate the RMS value of the V samples, and the RMS value of
the A samples, and then multiple that together and call it Apparent Power.
Can this be done by looking at the V*A samples alone? If so, how? If not,
why not?
Thanks,
Alan
Let's say I start with 120VAC and 2A, both RMS. If I generate samples for
one cycle @ 60hz, I will have voltage samples raning from -169.7V to 169.7V,
and current samples from -2.83A to 2.83A. Let's say I then make the current
lag behind the voltage by 45 degrees, and I multiply the V sample by the A
sample to get a VA sample, I get these three graphs from Excel:
http://home.earthlink.net/~alank2/pf.gif
The top one is voltage, the middle one is amps, and the bottom one is V*A
(watts).
If I average all the samples in the V*A chart, I believe I will get True
Power (watts) from this measurement.
My question is, without the V or A samples, just the V*A samples, can you
calculate the Apparent and Reactive Power?
It seems to me that looking at the graph (bottom one) that there should be a
way, but I can't figure out how to do it.
I was able to calculate the RMS value of the V samples, and the RMS value of
the A samples, and then multiple that together and call it Apparent Power.
Can this be done by looking at the V*A samples alone? If so, how? If not,
why not?
Thanks,
Alan