[Prev][Next][Index][Thread]
Re: MOT saturation tests II
Hi Bill,
> Original Poster: "Bill the arcstarter" <arcstarter-at-hotmail-dot-com>
>
> Coilers,
> While the rest of the world was watching baseball on TV, I was out in
> the garage chiseling the shunts out of my MOT. I'm now left with the
> main laminations and the primary winding. The shunts and the secondary
> windings are long gone, having fallen to the chisel!
>
> I then remeasured the current as a function of voltage. Here are the
> new results:
>
> (I added the two rightmost columns)
>
> V=volts, I=amps, Z=complex ohms
> V Iold Zold Inew Znew
> 50 0.26 192. 0.27 185.
> 60 0.31 194. 0.31 193.
> 70 0.38 184. 0.38 184.
> 80 0.50 100. 0.50 160.
> 90 0.73 123. 0.74 121.
> 100 1.16 86.2 1.20 83.3
> 110 2.14 51.4 2.35 46.8
> 120 3.86 31.1 4.41 27.2
> 130 5.90 22.0 6.80 19.1
>
> I'm surprised that removing the shunts really didn't do anything to the
> behavior of the transformer! The main difference is a slightly
> increased current draw at the higher voltages.
>
> At this point I can only guess that the purpose of the shunts was to
> limit the current flowing into the secondary (just like a NST or
> welder). It seems that, as far as using MOTs as current limiting
> devices for pigs, the shunts really have little or no effect.
>
> Comments invited!
The shunts only come into play when flux opposition caused by a load
on the secondary funnels primary flux into the shunts. This is what
gives rise to the high leakage inductance of the transformer -
leakage because any flux in the shunts is not directly coupled into
the secondary.
Malcolm