Re: MOT current limiting shunts

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

Original poster: "Sean Taylor" <sstaylor-at-uiuc.edu> 

 > To determine the apparent ohmic resistance of the
 > transformer as seen from the primary (there is probably a better term
 > for this), first measure the resistance of each winding. Then divide
 > the secondary resistance by the turns ratio of the transformer. Add
 > the primary resistance to this. The result is the apparent resistance
 > as seen from the primary.  This resistance will appear in series with
 > the leakage inductance in series with the primary.

You have to divide by the turns ratio SQUARED - the equivalent resistance of
something on the other side of the transformer is scaled by the turns ratio
squared.  Say you have a 120/12V transformer, N = 10, and a 12 ohm load on
the secondary.  The secondary draws 1 amp, and the primary draws 1/10 amp.
Requivalent = 120/(1/10) = 1200 ohms, or 12*(10^2).

Sean