RE: any insulation recomendations for magnet wire

["John H. Couture" <couturejh-at-worldnet.att-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Malcolm has brought up one of the many reasons why it is so difficult to
develop an empirical TC computer program compared to a program or simulator
that uses only theoretical equations. The empirical type programs uses data
that can be interpreted in more than one way so are controversial. The
theoretical type program uses equations that are accepted by all. The JHCTES
Ver 2.3 is an empirical type program and is based on both theoretical
concepts and on empirical data.

One of the parameters used by the JHCTES Ver 2.3 program is volts/turn
because this can be used as a benchmark by designers to  select the proper
secondary wire insulation. However, there are situations where the
insulation value is so great there is little chance for the coiler to get
into trouble, see example below.

The total voltage vs total secondary length was suggested as a parameter.
Note that this can be easily found with the JHCTES program because voltage
and length are both shown as parameters. However, this would be another
empirical parameter subject to controversy. Someone would have to find an
empirical equation so the designer can use it in his design.

Your example using 6 KV brings up an interesting situation when magnet wire
is used by the coiler. Several years ago when I was developing the JHCTES
program I tested several wire insulations including magnet wires. I found
the enamel insulations to vary from about 3 KV to 8 KV for breakdown
voltage. Using your example the 8 KV would give 16 KV between turns times
1000 turns equals 16 million volts. It is obvious why Wingate, Hull, an
other coilers had few insulation problems with their coils using magnet
wire. However, other types of insulation like vinyl aren't so accommodating.

John Couture

---------------------------

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, July 17, 2000 6:21 PM
To: tesla-at-pupman-dot-com
Subject: RE: any insulation recomendations for magnet wire


Original poster: "Malcolm Watts" <M.J.Watts-at-massey.ac.nz>

Hi John,
         I'm not sure that V/turn is a particularly useful
concept when it comes to rating resonator insulation. An
example: I can test a certain gauge of wire (with a
correspondingly thick coating of polyesterimide or whatever)
to 6kV without it breaking down between two adjacent pieces of
the same wire. More actually - I'm being conservative. So,
let's say we have a coil actually doing 6kV/turn and
furthermore that coil has the "standard" 1000 turns. I can
wind something like that with a height of less than a metre.
But can I get output to hit the insulation limit of my wire?
Not a show in hell - we're talking about 6MV over a distance
of less than 1m. Cannot be done without winding flashovers.
Generally one finds that the tracking distance required to
prevent a flashover does not adhere linearly to the total
voltage.
      I bet there are very few if any coils which even come
close to taxing the turn-turn wire insulation. I think your
program should instead be looking at total voltage/total
secondary length.

Regards,
Malcolm