What devices are required to do Fluorescent Dimming?

[ETsang]

Anyone know?

[Anonymous user]

combination of Cbus Analogue output & relay is required

[sesa96364 · Accepted solution]

First you need fluorescent loads that are compatible with phase control dimmers, 0-10V controllers or DALI.

Using a C-Bus 0-10V controller (L5504AMP) or a C-Bus to DALI interface (5502DAL) with these devices is a simple solution in terms of compatibility. The compatibility, loading restrictions and limits have all been worked out for you.

The requirement for CFL dimming has appeared since incandescent globes are being phased out in some countries.

CFL's are a bit of a problem when it comes to lighting control although some success has been reported with C-Bus leading edge dimmers (5508D1A).

Some problems that occur as a result of dimming CFL's are as follows:

- not all CFL's are dimmable, the CFL must specify that it is compatible with phase control dimming

- CFL's can flicker at low levels

- CFL's require a long kick start period (>1 minute) to warm up before dimming

- dimmer channels must be down rated to account for the continuous peak current of a CFL (the average power is low, however the peak current is high)

Some solutions for dimming CFL's:

- limit the minimum dimming level of a dimmer to >10% to prevent low level flicker

- the maximum number of CFL's per channel must be worked out by looking at the loading capacitance and the peak current. The limit per channel is going to be something like 20% of the channel maximum power rating. If a channel is rated at 240V 1A, the maximum CFL loading per channel is  likely to be (240W per channel x 20%) = 48W. For 17W CFL's, the maximum number of globes is 2 (2 x 17W = 34W).

Because there are such a variety of brands and models ensure you test the fluorescent load/ballast and dimmer combination for performance and acceptable behaviour before fitting out a site.

Regards,

Matt