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Re: MOTs in series
Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
At 07:25 PM 1/2/2007, you wrote:
This is probably a stupid question, but I was wondering what exactly
the problem with having several MOTs in series is. The web sites
that I have found that discuss this topic all say that the problem
is that the insulation on the secondary isn't sufficient to prevent
arcing to the core, but what if the core is at high voltage as well?
The voltage rating from core to primary isn't all that wonderful
(probably something like 2kV for a HiPot test to get UL)
Like, if the secondaries were strung together, with the hv output
of one secondary attached to the core of the next MOT?
Yes. On MOTs, the "cold" end of the HV secondary winding is
connected to the core. Physically, that's the inner layers, so the
insulation requirement is reduced. MOTs are a VERY cost sensitive
application, so they don't spend a penny more on kraft paper or
varnish than they absolutely need to.
I think that each MOT would not have a potential difference from
the secondary to the core of more than the original rating for a
single MOT, and since the primaries are electrically isolated from
the high voltage across the secondaries, arcing to them shouldn't
be a problem, unless maybe something on the secondary was
grounded. Is this correct?
Primaries are electrically isolated, but not with enough breakdown
strength to run a series string of MOTs. It "might" work with two in
series, for a while.
Also, I was wondering if you could parallel the primaries instead of
connecting them in series, so that different MOTs could be connected
to different outlets/circuits/breakers (assuming they were all in-phase).
Thanks a lot,