RE: Ballast choke questions

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

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi

Here is some interesting reading on the subject. 
http://www.staff.ncl.ac.uk/r.e.burnett/parts2#ballast
Richie has a nice ballast there.

I am interested to see what you do and how it works.

later

deano

> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Tuesday, May 08, 2001 11:50 PM
> To: tesla-at-pupman-dot-com
> Subject: Ballast choke questions
> 
> 
> Original poster: "J. B. Weazle McCreath by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>" <weazle-at-hurontel.on.ca>
> 
> 
> Hello Coilers,
> 
> I've spent the last two evenings disassembling a large transformer
> that I acquired with the intent to rewind it as a ballast choke to
> use with a 5 KVA pole pig I'm getting.
> 
> The stack of E and I laminations measures 3.5 inches thick, with
> external dimentions of 7 inches by 7.75 inches.  The center most
> leg, or the middle of the E measures 3.5 inches by 2.25 inches.
> The two "windows" measure 5 inches by 1.5 inches.
> 
> Now for the questions to you transformer and choke experts:
> 
> 1) How much power should a core of that size be capable of?
> 
> 2) When re-assembling the core, should the laminations be
>    put back interleaved as originally found, or should all
>    of the E's be put together facing the same way?
> 
> 3) If all E's are aligned, should there be an insulator put
>    into the gap between the E's and the I's?
> 
> 4) I'm going to put multiple taps on the choke windings for
>    selecting different currents.  Should the first 79 turns
>    as per the table below go nearest to the core, or on the
>    outside of the windings?
> 
> Quoted from a post by Bert Hickman:
> 
> >The example below assumes a 250 turn ballast
> >and a 10:1 current range in 10% increments.
> >
> >  
> >           Multiplying   Turns
> >            Factor:      at Tap
> >
> >   Nmax      1.00        250    Total number of turns (Max. L)
> >   N(90%)    0.95        237
> >   N(80%)    0.89        224
> >   N(70%)    0.84        209
> >   N(60%)    0.77        194 
> >   N(50%)    0.71        177
> >   N(40%)    0.63        158
> >   N(30%)    0.55        137
> >   N(20%)    0.45        112 
> >   N(10%)    0.32         79
> >
> 
> Any and all comments are welcomed.  I want to do this once and do
> it right the first time.  Thanks in advance.
>  
> 
> 73, Weazle, VE3EAR/VE3WZL
> 
> Listening: 147.030+ and 442.075+
> E-mail:    weazle-at-hurontel.on.ca
>            or ve3ear-at-rac.ca
> Web site:  www.hurontel.on.ca/~weazle
> 
> 
>