Re: [TCML] insulation

["David Rieben" <drieben@xxxxxxxxxxx>]

Hi Douglas,

Ther is a reason that you cannot series NSTs, namely
that the HV secondary windings are almost always
center tap grounded to the core. The label will say
that the secondary is "mid-point grounded". IF a 12
kV NST is midpoint grounded, then that means that
each HV bushing is only 6 kV, realtive to ground and
are 180 degrees out of phase with each other. That's
how you obtain 12 kV between the two HW bushing
terminals, but only 6 kV between each terminal and the
grounded case. Now if you were to try to series the 12
kV secondary with the 12 kV secondary of another
NST, you would only be able to develop 12 kV max
between the 6 kV-to-ground of the first NST and the
6 kV-to-ground of the other NST. The reason the
manufacturers mid-point ground their NSTs is to
cut the required  insulation, since they only have to insulate
the secondary for half of its full rated output voltage,
relative to ground. So unless you were to totally dismantle
the NST and disconnect the midpoint ground of the
secondary to the core ground (which would be very
difficult and impractical and likely result in the destruction
of the said NST), then you cannot series the outputs
of two or more NSTs.

However, you can PARALLEL NSTs of the same
output voltage rating to add their currents. Example:
You can parallel (2) 12/30 NSTs to get 12 kV @
60 mAs. More current is the secret to increased Tesla
coil performance anyway. Just make sure that the
outputs of the two or more NSTs are in phase. When the
the output leads of the two or more NSTs are brought
together to parallel, they should NOT draw an arc. If
they do, then simply reverse the 120 volt input leads.

David Rieben


----- Original Message ----- 
From: "douglas smith" <eyemfedup2@xxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, June 20, 2008 9:29 PM
Subject: [TCML] insulation


OK ill try this again i had posted an earlier question about if i could 
modify an nst by making the core so as to except two secondaries in series 
on each side and what would the effects be.
one reply told me that i would have insulation problems.
i am curious as to what that means .
where would i have the problem? and can anyone out there help me with what 
material i could use to fix it. surely there is a way to get around it all 
things are possible.
it just seems logical that it would work in my humble opinion.
i cant be the only idiot out there that has thought of this.
hopefully this is more proper and will make it to the list.



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