GB835371A - Alternating current supply apparatus for electric discharge devices - Google Patents

Abstract

835,371. Discharge lamp circuits; transformers. BASIC PRODUCTS CORPORATION. May 19, 1958 [May 20, 1957], No. 15962/58. Classes 38 (2) and 38 (4). A circuit for a high-pressure mercury vapourdischarge lamp comprises a leakage transformer 10-13, Fig. 2, having two primary windings connectable in series or parallel, capable of saturating the core and a tapped secondary winding 13 connected across a capacitor 37 and arranged to resonate at odd harmonic frequencies, preferably the third. The lamp 45 is connected across a part or whole of the secondary winding 13 in series with a capacitor 43 and an opposing voltage developed on a portion 29 of one primary winding, or a separate winding on the primary core. On starting, the fundamental and harmonic voltages are additive and sufficient to start the lamp, which on striking damps the circuit reducing the voltage to its operating level. Suitable values for, and construction details of the components are given in the Specification. The transformer core 10, Fig. 1, comprises a substantially rectangular outer member and a central leg 15 forced into position to give metal to metal contact and which is held by rivets 27, 28. A high reluctance shunt 21-26 having an air gap is provided between the primary and secondary windings, the limbs 23 24 being of unequal length.