Dimming of fluorescent lamps

Abstract

Now that controlled semiconductor devices are available, modern lighting control equipment can be made simpler and smaller than was possible when the only control devices were thyratrons and variable resistors or transformers. Semiconductors are being used more and more where continuously variable lighting is required — not only indoors (e.g. in theatres, lecture rooms, etc.) but also out of doors (e.g. in road tunnels). In factories too, where a constant lighting level is to be preferred, the fluctuating daylight can be supplemented by automatically controlled variable level artificial lighting.