Re: C-Bus and Wire-wound transformers - HELP

["Robert Crawshaw" <golcarbob@xxxxxxx>]

http://www.electrical-distributors.co.uk/cat/itm00787.htm

never used one, never bought one from them, just found it with a google
search,

ive got a 1Kva wirewound one, somewhere, THAT doesnt buzz when dimmed ?
but i also have a 300va one that does,  depends on the quality of the
transformer i spose, the big one is resin dipped if i recall, so the
transformer laminations dont rattle about under hi current.


Regards

Robert Crawshaw
----- Original Message -----
From: "Bruno Prior" <bruno@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Wednesday, July 30, 2003 8:11 PM
Subject: [ukha_d] C-Bus and Wire-wound transformers - HELP


> In my barn conversion, I've gone for Hi-wire lighting (i.e. the type
> with parallel tensioned wires bridged by the individual light
fittings),
> running parallel with the purlins, as we have no ceiling for hanging
> conventional lights and we wanted to make the lighting as unobtrusive
as
> possible. Some of the runs are quite long (6 metres) and pretty high
up
> (over 5 metres from the floor), so I wanted to get more than 4 x 50W
or
> 6 x 35W bulbs per run. That pushes me to a transformer over 200VA. The
> next step up seems to be 300VA, which is plenty. But unfortunately, it
> only seems to be possible to get wire-wound transformers of this size,
> not electronic.
>
> I'm using C-Bus for control and have gone for the 2A per circuit
> dimmers, so they ought to be able to handle a 300VA load just fine.
But
> the wire-wound transformers make the most god-awful racket when the
> circuit is dimmed (and the original transformers we tried even made
> quite a din at full load). Our lighting supplier and C-Bus supplier
seem
> to be agreed in retrospect that C-Bus dimmers don't work well with
> wire-wound transformers, although I had understood in the first place
> that this shouldn't be a problem. Just to make matters worse, the
> lighting supplier says that Hacel (the Hi-wire manufacturers) don't
> recommend using electronic transformers with their kit (apparently due
> to voltage drop on longer runs), but we might get away with it with
runs
> of 6 metres or less.
>
> I know there are some clever electrical bods on this list. Have people
> come across this problem before? And is there a way round it? Does
> anyone know where I could find a 300VA electronic transformer or a
> wire-wound transformer that doesn't make a racket when dimmed by
C-Bus?
>
> Cheers,
>
> Bruno
>
>
>
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