Re: Multi-Mini Transformers

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

Original poster: "Jolyon Vater Cox by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

but aren't those the maximum ratings with no safety margins / shouldn't we
try to limit the voltage to at least half of that?

Jolyon.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, June 20, 2003 2:29 PM
Subject: Re: Multi-Mini Transformers


 > Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
 >
 > Many transformers are designed for a 2000V or a 5000V isolation rating
 > (particularly those that might be connected to the phone network..)
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Thursday, June 19, 2003 8:34 PM
 > Subject: Multi-Mini Transformers
 >
 >
 >  > Original poster: "Jolyon Vater Cox by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
 >  >
 >  > Has anyone on the List ever used a "multi-mini transformer" approach to
 >  > implementing a high-voltage power supply for TC use?
 >  >
 >  > By multi -mini transformer I refer to practice of using many mains
 >  > step-down transformers "in reverse" with the mains windings connected
in
 >  > series to provide the required high voltage.
 >  >
 >  > I was originally thinking connecting the low-voltage windings in series
 >  > also, to connect across the mains supply
 >  > e.g. if the voltage rating of each winding were 6 volts then to
facilitate
 >  > connection to the UK mains supply of 240V AC, forty transformers would
 > need
 >  > to be connected (6V x 40 =240V on the "primary side
 >  > and on the secondary side, 240V x 40 =9600 volts, in theory.
 >  >
 >  > But looking at this again it appears there may a problem with the
 >  > interwinding/ core insulation
 >  > which may be insufficient to withstand the high voltages involved; for
 > with
 >  > a (non-grounded) voltage of 9600V on the secondary and 240V on the
primary
 >  > the interwinding insulation on the transformers nearest to the ends of
of
 >  > the "stack" would be stressed by a maximum of (9600-240)/2 =4680 volts.
 > Are
 >  > mains transformers likely to be rated to withstand this?
 >  >
 >  > Couldn't this percieved problem be mitigated to some extent by
"floating"
 >  > the low voltage winding, plus the core, of each of the "output"
 > transformers
 >  > -by feeding it with low voltage from an identical "isolation"
transformer
 >  > -driven from the mains-
 >  > so that every one of the low voltage links between the input and the
 > output
 >  > transformers would be isolated from the mains, mains ground and other
 >  > transformers in the stack?
 >  >
 >  >
 >
 >
 >