Re: Inductance calculation.
Bjørn, Tue Mar 28 2006, 01:52PM

Inductance, henry (H) = Wb/A = m^2 · kg · s^-2 · A^-2

Re: Inductance calculation.
WaveRider, Tue Mar 28 2006, 01:53PM

Wayne,
You are pretty much correct, except it is often more useful to specify
Weber/(Ampere-turns) since the flux-current-inductance relationship looks like
where L=inductance, I=amperes, N=# turns and F=flux (Webers, V-seconds or Tesla-m^2)...

Re: Inductance calculation.
GODSFUSION, Wed Mar 29 2006, 12:16AM

Ive never had to deal with inductance before, i was just curious as to how to find it. Specifically concerning something like a transformer, i wouldent know the number of turns. What do i do in that case?

- Wayne -

Re: Inductance calculation.
Bjørn, Wed Mar 29 2006, 12:55AM

http://wiki.4hv.org/index.php/LC_Oscillator

This should give enough information that you can measure it.

Re: Inductance calculation.
Part Scavenger, Wed Mar 29 2006, 02:41AM

Easy. First you find the impedance, basically the 'AC resistance', by running a low AC voltage through it and measure the current draw. Let's say you use 12VAC, and you read 1A.

Using Ohm's AC law, V=IZ, we compute:
12V=1A*Z
Z=12 ohms

Now, we use the formula: (2)(pi)(f)(L) = Z
Z is 12 ohms, and f is the frequency of the 12VAC which in my case is 60Hz.
Solve:
12 Ohms = (2)(pi)(60)(L)
Inductance = 31.85 mH

BTW, usually the # of turns on the primary of an MOT is between 100 and 120. Inductance usually varies between 7-30something mH with MOT ballasts. (Quick check with my LCR)