GB721125A - Improvements in and relating to street lighting apparatus - Google Patents

Abstract

721,125. Supply systems for space discharge apparatus; installation wirings ; transformer arrangements. BRITISH THOMSON-HOUSTON CO., Ltd. Aug. 13, 1953 [Aug. 14, 1952], No. 22353/53. Class 38 (4). An electric discharge lamp street lighting apparatus comprises a relatively large highreactance high-voltage main transformer 5 located outside a lamp luminaire 3, e.g. within a pedestal 2 at the base of the standard 1 which supports the luminaire, and, disposed within the luminaire 3, a plurality of two-terminal lamp holders 12a ... 12h for connecting in a series loop across a pair of conductors 7, 8 leading from the main transformer secondary winding 19 a plurality of two-terminal preheatable electrode elongated discharge lamps 11a ... 11d and a relatively small lamp electrode pre-heating transformer 9 having its primary winding 22 connected across the conductors 7, 8 and a plurality of low voltage secondary windings 23 connected across the lamp holders to supply heating current to the electrodes. The apparatus permits preheatable electrode fluorescent discharge lamps to be run from the existing constant current conductors of a series incandescent lamp system and obviates locating the large main transformer adjacent the luminaire or running a number of high voltage-to-earth electrode heating cables within the standard. Automatic reduction of electrode heating current when the lamps are running is provided by the high reactance nature of the main transformer 5. The lamps are heated to electron emission by electrode voltages below the ionization voltage of the lamp gas or vapour, and starting is facilitated by means which establishes a potential gradient along the lamps, e.g. an electrically conductive coating (not shown) and by a capacitor 24 connected in shunt with one or some of the lamps, and as shown, two adjacent lamps 11a, 11b.