RE: MOTs in series

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>

Once I acquire a few more MOTs, I'll probably try a similar 6-MOT 
design, but was wondering what would happen if the core did actually 
arc to the primary.  Wouldn't this cause a high-voltage spike in the 
house's electrical system?  Since the voltage isn't that high, would 
a safety gap be sufficiently reliable to protect against this?  Also, 
when you said that the center of the string of series connected MOT 
secondaries is at ground potential, you mean the middle 2, with those 
middle 2 cores being connected together, right?

Thanks,
Chris


-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wed 1/3/2007 2:50 AM
To: tesla@xxxxxxxxxx
Subject: RE: MOTs in series

Chris,

The practical limit for MOTs in series is four in air and six or 
eight under oil.  This assumes the center of the string of series 
connected MOT secondaries is at ground potential.  Not only do you 
have to worry about the secondary arcing to the core, but also the 
core arcing to the primary, if the core is at elevated potential.

Yes, you can parallel primaries.  I have 6 MOTs with the secondaries 
in series, under oil.  The 120 volt primaries are in two banks of 
three in parallel, each bank going to a different circuit breaker in 
my house breaker box.  The outlets/breakers don't have to be in 
phase, since you can swap the connections on the primary.  Mine are 
not so as to balance the load across my 240 volt feed.
--Steve


________________________________

From: Tesla list [ mailto:tesla@xxxxxxxxxx <mailto:tesla@xxxxxxxxxx> ]
Sent: Tuesday, January 02, 2007 8:26 PM
To: tesla@xxxxxxxxxx
Subject: MOTs in series

Hello,

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?  Like, if the secondaries were strung together, with the hv 
output of one secondary attached to the core of the next MOT?  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?
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,
Chris

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