Re: C-bus Channel won't turn off...

[Robert Kearns <robkearns@xxxxxxxxx>]

Hi Keith,

My system was installed around the same time as the big debate was going on
and unfortunately I didn't read about the issue until after mine was almost
finished. I have a single MCB covering one enclosure with 3 x 8 channel
dimmers.

I've had three halogen bulbs blow before on the same channel without any
damage. The mcb usually goes but that's all. Most of my lights are LV
downlighers which, touch wood, I've had no blown bulbs with.

In the dinning room and kitchen I have some temporary mains voltage light
fittings, the type with a long bar and adjustable fittings, that blown
quite
frequently, Usually when the children are jumping around in the room above.
Could it be a dodgy fitting or are halogens very susceptible to vibration
damage? The lights do vibrate significantly when the children are at work
above!

Would LV halogens be less likely to cause damage to the channel as the
transformer has some sort of short circuit protection? Does the protection
cut off all current on the channel or does it just protect the internal
circuits of the transformer?

Thanks
Rob

On 11/15/05, Keith Doxey <ukha@xxxxxxx> wrote:
>
> Hi Robert,
>
> > I had a downlighter blow this evening which tripped the mcb that
> > covers the whole 8 channel dimmers. After resetting the mcb all
> > channels are ok except the one that blow,
> > It's on but I can't turn it off.
> >
> > The led on the switch goes on and off, and I can see the network
> > messages in the C-Gate window, but the actually lights don't
respond.
> >
>
> Classic symptoms of a blown triac :-(
>
> Triacs normally fail Short Circuit so that the load is permanently
> powered.*
>
> Lutron also have a relay in their dimmers that physically disconnects
the
> load when OFF. This means that in the event of a blown triac, you
still
> have
> basic ON/OFF control of a load. Having said that, Lutron use such over
> specced triacs that it is virtually impossible to blow one!
>
> Do you have individual MCB's on each channel or just a Master MCB ?
>
> Low value MCB's on each channel, or a low value Ultra Fast fuse on
each
> channel is the best way to protect a dimmer. IF you had individual
MCB's
> then it might have tripped fast enough to protect the triac although
there
> is no guarantee of that, but at least you would be able to turn that
> channel
> OFF by flicking the breaker off.
>
> Above is general advise regarding dimmers as I dont actually have CBus
but
> have fixed lots of blown triacs.
>
> Regards
>
> Keith
>
> * One lighting controller I repaired had failed "open
circuit"..... al
> least
> I'm pretty sure it did because all that was left of the triac was
three
> legs
> sticking out of the PCB and a blast mark on the inside of the case!!!!
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>


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