RE: ballast bobbin...again

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

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-uswest-dot-net>" <gloudner-at-SINTE.EDU>

Hi Chris

I have made low voltage bobbins by wrapping craft paper, which has been
saturated with epoxy glue, around a form to the desired thickness. The
result is a rock hard bobbin, but the job is messy and sticky. Put some
spacers between the form and the bobbin so you can easily remove the bobbin
off the form. Since you are using # 8 wire, you will need a rock hard
bobbin. It going to be difficult to pull that wire tight by hand.

Godfrey Loudner 


> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Wednesday, May 02, 2001 12:22 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Re: ballast bobbin...again
> 
> Original poster: "Metlicka Marc by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <mystuffs-at-orwell-dot-net>
> 
> i have an inductor from a 75 hp ac drive that is wound from flat wire
> and uses spacers to hold each layer away from the others it is wound in
> an oval over the square core. i thought this might be for cooling? i
> will be sending jim a pic for his "hv components" data base of things to
> look for. 
> marc m.
> 
> Tesla list wrote:
> > 
> > Original poster: "Pete Komen by way of Terry Fritz
> <twftesla-at-uswest-dot-net>"
> <pkomen-at-zianet-dot-com>
> > 
> > FWIW: I have an isolation transformer (1kva, 120v to 120v) in which the
> > secondary is about 3/4 to 1 inch away from the core.  It has cardboard
> > spacers to keep the clearance.  It works fine.
> > 
> > Regards,
> > 
> > Pete
> > 
> > -----Original Message-----
> > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > Sent: Tuesday, May 01, 2001 11:34 AM
> > To: tesla-at-pupman-dot-com
> > Subject: Re: ballast bobbin...again
> > 
> > Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> > <jimlux-at-earthlink-dot-net>
> > 
> > This would work fairly well.  Very large transformers (1 MVA and up) use
> > laminations that are of different sizes so that they can approximate a
> > circular cross section. Transformers where cost is important use square
> or
> > rectangular cross sections because it is cheaper (they make those E and
> I
> > sections by the millions)
> > 
> > I doubt that the leakage reactance increase from spacing the windings
> away
> > from the core would be all that significant, assuming that you don't
> have
> > an air gap in the core.  HV isolation transformers are often made with
> the
> > HV winding as a separate "donut" that is slipped over the core
> laminations.
> > 
> > Tesla list wrote:
> > >
> > > Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> > <CTCDW-at-aol-dot-com>
> > >
> > > Hey all!
> > >
> > > I have a quick question. In my search for a suitable bobbin material,
> I am
> > > wondering how close the wire need to be from the core. I assume that
> right
> > on
> > > the core is the best, but can I wind on PVC pipe and put the core
> inside?
> > It
> > > is a straight core. I could actually get some more steel and
> completely
> > pack
> > > the pvc inside so it would be a more or less round cross section.. any
> > help
> > > would be appreciated! :)
> > >
> > > THanks!
> > >
> > > Chris W
> 
>