C-Bus and Wire-wound transformers - HELP

[Bruno Prior <bruno@xxxxxxx>]

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