RE: 1600 watts magnetizing current?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

 >How do you work out power factor when your
 >voltage and current are non sinuosidal(we have baad waveform distortion
 >here)?

Well, nowadays you use a "power analyser" that digitises the line voltage
and current waveforms, and does the analysis for you. I wrote a program that
did this using voltage and current transformers plugged into the line-in of
a PC soundcard, but I never had the guts to try hooking it to a Tesla coil
;) If anyone wants the software to play with, they're welcome, but you need
to download the 11MB LabView Run Time Engine to make it go :(

You can also snapshot voltage and current with a 2-channel digital scope,
and do the calculations on a computer.


The basic idea is to do a Fourier analysis of the voltage and current
waveforms. This decomposes them into a combination of sine waves at 60, 120,
180, 240 Hz etc. 60Hz is the "fundamental" and the rest are the "harmonics".

Then you work out the real and reactive powers for the fundamental and each
harmonic (using the equations I posted, as you are now dealing with
sinusoids) and add them all up (taking care to get the signs right)


If your line voltage is almost sinusoidal, and only the current is
distorted, it gets a bit easier, as you know that only the fundamental of
the current waveform can produce any real power, and all the power
associated with harmonic currents must be reactive.

In this case the math simplifies to:

S=Vrms*Irms
P=Vrms*I(0)*cos(phi) where I(0) is the RMS value of the fundamental current
and phi is the phase shift between Vrms and I(0)

Displacement power factor=cos(phi)
Harmonic power factor=I(0)/Irms
Overall power factor=(displacement PF *  harmonic PF)= P/S =
I(0)*cos(phi)/Irms

http://www.microconsultants-dot-com/tips/pwrfact/pfarticl.htm

Steve C.