GB722823A - Improvements in or relating to operating systems for a discharge lamp - Google Patents

Abstract

722,823. Transformers; control systems for space discharge apparatus; automatic regulation. HANOVIA CHEMICAL & MANUFACTURING CO. Jan. 31, 1952, No. 2661/52. Classes 38 (2) and 38 (4). A system for varying the output of a discharge lamp 20 yet maintaining the output substantially constant at the selected level despite supply voltage fluctuations comprises, in combination, a transformer having mounted on a magnetic core structure 12 and spaced by a high reluctance magnetic shunt 13 primary and secondary coils 14, 15, the latter being on a part of the core which saturates during an appreciable part of each half-cycle of the alternating supply current, a movable commutating device to select, directly or indirectly, the secondary coil output voltage between predetermined limits, and the lamp 20 serially connected with a capacitor 19 of 1¢ to 6 times its KVA rating to the commutating device and across at least part of the secondary coil for operation under the ballast provided by the capacitor and the secondary coil reactance. The overall ballast is capacitive and the core saturation provides the constant lamp output feature. As shown, the lamp is a vapour arc lamp, and the commutating device comprises a brush 23 which contacts the turns of an auxiliary coil 21 connected between secondary coil tappings 16, 18; but in another embodiment, Fig. 2 (not shown), the brush contacts directly the secondary coil turns.