Re: [TCML] Ballast Question

["garry neeley" <bamacoiler@xxxxxxxxx>]

It is exactly a single pig from a 3-pig, 3-phase bank.  It is single phase
but only has 2 lv bushings.  It does have a 480v primary exactly like you
described. 50kva. But it is the only pig I have so...  No problems with the
ballast behaving properly?

Garry Neeley

On Tue, Aug 19, 2008 at 2:13 PM, David Rieben <drieben@xxxxxxxxxxx> wrote:

> Hi Garry,
>
> No, I don't see any problem with doing this but my
> question is why do you need the extra 240-480 step
> transformer in the circuit, unless the low voltage side
> of your pig happens to be 480 volts rated instead of 240.?
> 480volts plus the boost from the variac would yield on
> the order of 550 to 600 volts into the low voltage
> side of the pig and if it is only rated at 240 volts,
> this would severely overvolt and saturate the core
> of the pig. Also, if it actually is rated at 480 volts
> across its low voltage side, you could just use the
> center tap of the three low voltage bushings for a
> 240 volt rated input tap. It does have 3 LV bushings,
> doesn't it? I have seen 2 LV bushings on pigs that
> are designed to be a single pig in a 3-pig, 3-phase
> bank to provide a phase of 277/480Y, 3-phase
> service, but these are generally larger transformers
> (25 kVA or greater rated units).
>
> --
> David Rieben
>
> -------------- Original message --------------
> From: "garry neeley" <bamacoiler@xxxxxxxxx>
>
> > Hey guys I just have a quick question here. In my setup I'm gonna take
> 240
> > from the wall to a -280 v out variac to a-240 to 480 step up xformer to
> the
> > -ballast to the -pig. Do you guys think there will be any problems with
> > this because I have the extra step up transformer in the circuit? Any
> > thoughts, ideas?
> > Bamacoiler
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