RobertRoss,
Yes, you can do it that way, but your dividing by √2 to get the RMS value relies on the wave being sinusoidal. As others have pointed out, if nonsinusoidal, then that method does not give you the RMS value anymore. Also I²Z does not work either on a nonsinusoidal wave because something like a rectangular or triangle wave will have multifrequency components of different amplitudes. So what is the impedance "Z" of a component driven by a multifrequency wave? Have you ever seen anyone calculate or define it?
When finding the average, the units of time are unimportant because they all get cancelled by the division. I could have used sin(2*pi*60*t) and divided up the intervals by (1/60*(1/360) and gotten the same answer, with more computation. However, the degrees represent a time unit of something, so it works for the average. The important thing is to make the intervals even.
Wrong, the method of finding the true power from average the the VI product works for whatever shape the wave is as long as you have enough points to represent the wave.
Yes, as long as it is sinusoidal. If not sinusoidal, then use the method I outlined.
Now, the spreadsheet I sent you contains an error. The result is correct, but there is something wrong with the pair values at each point. Can you find the error?
Ratch
Question #1) I am curious to know if this can also be done the way I innitially posted this thread.
Yes, you can do it that way, but your dividing by √2 to get the RMS value relies on the wave being sinusoidal. As others have pointed out, if nonsinusoidal, then that method does not give you the RMS value anymore. Also I²Z does not work either on a nonsinusoidal wave because something like a rectangular or triangle wave will have multifrequency components of different amplitudes. So what is the impedance "Z" of a component driven by a multifrequency wave? Have you ever seen anyone calculate or define it?
Question #2)
True power is work per a period of time. In your .xls file, you summed all the instantaneous powers, you then divided the result by 360°. Is degrees of a circle considered as "time". Isn't time the period of the wave sine (1/60) ... confused.
When finding the average, the units of time are unimportant because they all get cancelled by the division. I could have used sin(2*pi*60*t) and divided up the intervals by (1/60*(1/360) and gotten the same answer, with more computation. However, the degrees represent a time unit of something, so it works for the average. The important thing is to make the intervals even.
Question #3) The method you have used will work on a sinuasoidal wave form only... right? If the AC wave I read is weirdly shape, then I would not be as precise with the True power calculations... right?
Wrong, the method of finding the true power from average the the VI product works for whatever shape the wave is as long as you have enough points to represent the wave.
Question #4)
If my Ac circuit has very little or no reactive power, can I still use the above calculations?
thanks
Yes, as long as it is sinusoidal. If not sinusoidal, then use the method I outlined.
Now, the spreadsheet I sent you contains an error. The result is correct, but there is something wrong with the pair values at each point. Can you find the error?
Ratch