Re: Multi-Mini Transformers

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

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?
 >
 >