GB643602A - Improvements in electric circuit arrangements and fittings for high-tension electricdischarge lamps - Google Patents

Abstract

643,602. Protective cut-out arrangements; switch cases. CLAUDE-GENERAL NEON LIGHTS, Ltd., and HIGGINS. C. March 8, 1948, No. 7127. [Class 38(v)] In a high tension discharge lamp installation, the protective enclosure for each hightension terminal has an earthing switch, which earths the terminal when a cover or panel is removed, so as to cause the operation of an earth-leakage protective arrangement to interrupt the supply to the installation. In Fig. 1, four tubular lamps 1 are connected in series across the secondary winding 2 of a transformer having a primary winding 3 energized from supply terminals 4, 5, via the contacts 7, 8 of an electromagnetic switch, the operating coil 6 of which is connected between earth and the centre tapping of the winding 2. The enclosure 9, Fig. 2, for the end of each lamp, contains an insulator 11, connector 12, a cap 13 which fits the end cap of the lamp 1, and an earthing switch which makes contact with the connector 12 when a removable panel (not shown) is removed, so as to earth the high-tension circuit and cause operation of the electromagnetic switch. The earthing switch shown comprises a substantially U-shaped wire support 15 forming the pivot for a wire lever 17, 18 having a limb 18 biassed by the weight of ceramic beads 19 towards the connector 12, and a limb 17 which is engaged by the removable panel when replaced so as to move the limb 18 away from the connector 12. As an alternative the lever may be spring-biassed. The circuit may be provided with a voltage responsive relay, possibly a relay coil in series with a spark gap, connected across the secondary circuit, so that a rise in the high tension voltage due to an open circuit, causes the operation of the relay which opens the primary circuit of the transformer. The Provisional Specification describes an alternative arrangement in which the switch in each enclosure opens the secondary or high-tension circuit to cause operation of the voltage responsive relay when a panel is removed.