Fluorescent Lamps Double Lighting
Page 9
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TTECHNIQUE and future possibilities of fluorescent lighting in vehicles were reviewed in a paper read recently to a meeting of the Illuminating Engineering Society at Nottingham by Mr. C. Dykes Brown, A.M.I.E.E., and Mr. S. Anderson, B.Sc., both of the General Electric Co., Ltd.
They pointed out that most vehicle fluorescent installations in this country made use of hot cathode 18-in. 15-watt or 24-in. 20-watt lamps, which could be accommodated in compact fittings, and permitted greater 'flexibility of layout than would be possible -with longer lamps. Lamps of these dimensions could be operated from a supply of about 100 volts.
.Lower,Yoltages could be used, with shorter lamps, but their efficiency was generally: less s,and ,.they,,were. chosen -, mainly when there was some-, specialcircumstance in in their favour. The example was quoted of 15-in. 14-watt lamps in trolleybuses having a 60-volt battery for emergencymanteuvring. This battery would supply the lamps without requiring any -form of converter.
Normally, both in steam trains and buses only a 24-volt supply was avail able. It was advantageous to convert this to AC. at 110 volts and about 400 cycles, as -the gear used with the lamps ecitild then be made of small dimensions, and simple resonant starting circuits, without starter switches, were suitable.
Although, because of the use of a rotary, converter, only about 60 per cent, of the power drawn from the battery appeared at the lamps, it was 'still possible to obtain nearly double the _light from fluorescent Jamps,..'as coin-pared. with filament lamps,' for a given
drain on the battery, •