GB665103A - Improvements in and relating to electrical circuits for use with discharge devices - Google Patents

Abstract

665,103. Supply systems for space discharge lamps. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 28, 1948 [Jan. 28, 1947; July 24, 1947], Nos. 2582/48 and 2583/48. Addition to 658,750. Drawings to Specification. Class 38 (iv). In a starting circuit for a discharge device of the kind described in the parent Specification, wherein the heating circuit for the thermionic electrodes is separate from the discharge circuit and is arranged to be open-circuited upon the initiation of the discharge by an automatic switch actuated by at least part of the main discharge current, the circuit includes means comprising a glow discharge or resistance heated thermal switch, arranged to apply under delay a starting voltage upon closure of the heating circuit across the supply. When the starting voltage is applied to an auxiliary external electrode on the device this may be connected to an additional winding, in auto-transformer connection, on the heating transformer through the normally open contacts of a thermal switch resistance-heated from an additional winding on the heating transformer, Fig. 1 (not shown) ; alternatively the auxiliary electrode may be connected direct to an auto-transformer, the primary of which is connected across the electrodes of the device through a glow discharge switch and the actuating coil of the automatic switch, Fig. 2 (not shown). When the starting voltage is obtained by interrupting the current in a ballast choke a glow discharge switch may be connected across the electrodes of the device through the actuating coil of the automatic switch, Fig. 3 (not shown), or in the case when the automatic switch includes a voltage holding coil as described in the parent Specification this switch connects the choke and current actuating coil across the supply through a glow discharge switch which is disconnected when the automatic switch operates, Fig. 4 (not shown).