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Re: Transformer core (fwd)
---------- Forwarded message ----------
Date: Tue, 12 Oct 1999 05:07:04 -0400
From: Neon John <johngd-at-bellsouth-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Transformer core
Tesla List wrote:
>
> Original Poster: Bunnykiller <bigfoo39-at-idt-dot-net>
>
> i rewound a core of similar size for ballasting my pig...
> altho i feel Dr Rez can answer this one much better than I but i will
> give you my experiences ...
>
> i ground out the welds and rewound the core with #10 solid copper
> insulated .. after rewelding the I back on I tested it on 120 V with
> a current draw of 6 amps ... but here are the details ...
>
> there are 150 turns and there is also an air gap at the center leg to
> the I bar of .060 " ( increased reluctance e.g. more current draw) the
> ends ( outside legs) are flush ( minimal gap ) to the I bar. when the
> unit is used with the pig there is a current draw of 20 - 25 amps (
> seems to surge a bit ) the unit gets warm but not enuf to damage the
> insulation on the windings. btw im using 240 on the pig input ..
For another technique on chokes, check out http://neonjohn.4mg-dot-com
/files/neon/choke.jpg. (Sorry this web hosting outfit won't allow
one to click in directly - gotta see those ads. This is a choke I
wound to ballast a pole pig for my neon bench. The service
conditions are similar. The core is 10 lbs of mild steel gas
welding rods cut in half and wrapped in butcher paper. There are
170 turns of large wire (gauge? Est 8ga. What my friend at the
motor repair shop gave me.) This choke, when hooked to the variac
in files/neon/choke2.jpg connected as a choke (wiper, one end of the
stator), limits the pig primary current to 60 amps at about 3/4
scale on the variac. /files/neon/chokes.jpg shows a better view of
the choke along with a choke made from a Miller welding machine.
The choke in the foreground has a tap to let me have two different
ranges for different types of neon work.
This choke is fairly easily hand-wound and requires no special
tools. Cost can be as little as free, depending on where the
materials come from. I got the wire for free as an otherwise
unusable spool end from my friend's motor shop. An excellent source
for very cheap core steel is those little wires used to hold
fiberglass insulation between the joists of a house. Thousands of
them come in a box for just a few dollars and are available at Home
Depot, Lowe's, etc.
John
--
John De Armond
johngdSPAMNOT-at-bellsouth-dot-net
http://neonjohn.4mg-dot-com
Neon John's Custom Neon
Cleveland, TN
"Bendin' Glass 'n Passin' Gas"