I have a rather large(ish) 3Ph AC Supply, for some of our testing it is needed to know (roughly) the output inductance (@400Hz) of the supply.
The supply is a switcher, so not a linear amp and I thought I had devised a way to measure this but now the simple math is getting the best of me.
I ran the output of the supply to a resistive load and measured Vl-n and phase current (Load is Y cfg) and used an oscilloscope to measure the Phase angle created.
much as I expected the voltage leads the current by a very small amount (2° or less)
but now I can't seem to get a reasonable way to back calculate the inductance.
Things I know:
Supply frequency (400Hz) Supply voltage (152.5 to 200VACrms)
Phase current (3.75 to 16.96 Arms)
Phase angle between V and I
So I could do
v = l di/dt but this gives me too high of #'s to be logical
Zl = 2*pi*f*l = V/I
What am I missing?
The supply is a switcher, so not a linear amp and I thought I had devised a way to measure this but now the simple math is getting the best of me.
I ran the output of the supply to a resistive load and measured Vl-n and phase current (Load is Y cfg) and used an oscilloscope to measure the Phase angle created.
much as I expected the voltage leads the current by a very small amount (2° or less)
but now I can't seem to get a reasonable way to back calculate the inductance.
Things I know:
Supply frequency (400Hz) Supply voltage (152.5 to 200VACrms)
Phase current (3.75 to 16.96 Arms)
Phase angle between V and I
So I could do
v = l di/dt but this gives me too high of #'s to be logical
Zl = 2*pi*f*l = V/I
What am I missing?
