RE: Dimmable fluorescent light, a soultion is required.

[Niall Shannon <niallshannon@xxxxxxx>]

The easiest and most efficient way of controlling a fluorescent light is to
buy a DSI fitting the fitting itself can be from any-one but the
manufacturer of the ballast is Tridonic.  The only other method that would
be recommended by Lighting designers, manufacturers and Consultants is 0
-10v dimming to use this method you would also need a relay to turn the
fittings on/off with DSI you do not the ballast controls the electrical
side
at all times on/off dim up/dim down.  Although DSI is more expensive it
will
give you the better return for your money.

C-Bus can control both of these standards of dimming easily and effectively
using either a 0-10v Analogue Module (give your installer a ballast spec
sheet) or a DSI gateway which has 8 channels and can control up to 100 DSI
fittings per channel.  So depending on the size of installation and cost
restraints etc.  it is your choice.

DSI  =  more expensive, smoother dimming, more cost effective over time,
less control gear required (C-Bus)

0-10v  = cheaper, not such a high level of dimming, dimming not always
smooth, Tubes "go" quicker than DSI but still not as fast as
conventional
wiring.

-----Original Message-----
From: Richard Malcolm-Smith [mailto:rich@xxxxxxx]
Sent: 07 July 2003 11:03
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Dimmable fluorescent light, a soultion is required.


Stuart Poulton wrote:

> Does anyone have any details and hopefully costings on dimmable
> fluorescent lighting ?
>
> Also, is it possible to control such lighting using C-Bus or Polaron ?

To dim fluros signifigantly, you need to make the heaters at the ends of
the

tubes run all the time.

If dimming to 70% or so is ok, it can be done, Get either a 3 wire dimmer
(Most
high power ones) or run a small incandesant light on the dimmer too.

Also, you must remove all the power factor correction capacitors from the
fluro
fitting.

If you dim too much, the tube will go out, and the starter will close to
try
to
re-strike the tube. Dont leave it like this or you will blacken the
ends/kill
the tube, the preheat on a starter based fluro fitting is enough to get the
ends
glowing, and tubes dont last long in that state.

If you need more dimming, there are what are called filiment transformers,
These
take the full 240 volt, and develop a seperate DC source to drive the
heaters at
a sane amount. You need both dimmed and undimmed 240 at the fitting. These
are
wired with the 2 secondarys across the 2 ends of the tubes, and are powered
>from
the undimmed 240 volt. When these are fitted, turning the light on will
gradually flicker up to full brightness over about 5 seconds when first
turned
on, like the old fasioned fittings with no starters (Because it drives the
tube
just like that) - keeping the heaters on wastes power, and some say reduced
tube
life, but mine seem to last fine.

Apparantly this will not work with the now more common slim tubes, but I
have a
stash of old fat 5 foot warm white ones so thats not an issue for me.

I can get 10 steps of dim on the X10, the 5 below that, the arc collapses
and it
just has a faint glow. The switching of the undimmed is done with a nasty
diode-capacitor-relay setup that buzzes sometimes, but hey, it works. Im
thinking of replacing it with a dolid state relay but why fix what works.

Anything that can drive incandesant loads should be able to drive the
fluros,
but if it gets the zero crossing from the mains and not the load (like the
x-10
ones) the inductive nature will mess it up at low levels. You will also
most

likly need a resitive load on it to hold the dimmer on, since the arc
doesnt

start straight away. 3 wire dimmers normally hold the triac on for the
duration
rather then pulse it, but you never know till you try it.


[Non-text portions of this message have been removed]