GB1185468A - Switching Device. - Google Patents

Abstract

1,185,468. Switching control of discharge lamps. ADMEL INTERNATIONAL Ltd. 7 Dec., 1967 [13 Dec., 1966], No. 55716/66. Heading H2H. A selector switching arrangement comprises a plurality of relays having first and second sets of contacts, and switch means for selectively connecting any one of the relay solenoids to a supply wherein the sets of contacts of the associated relay are closed. The relays are connected so that the second sets of contacts of any relay when closed shunts the solenoid of every other relay, and subsequently when the solenoid of another relay is connected to the source the shunt across its solenoid will be broken only after the first set of contacts of the previously energized relay have opened. A current limiting element is serially connected to each solenoid to avoid shunting the source. The arrangement may be used to connect an electrical device, e.g. a mercury vapour lamp 12 to a source via an element, e.g. a tapped winding 2, for supplying stepped values of electrical power. A keep-a-light circuit comprising a capacitor 20 and resistor 22 prevents extinction of the lamp on change over of contacts. The switches are mechanically interconnected so that only one is operative at any one time and in the operative position, a bridging piece connects the centre and right hand contacts. Operation of a switch 3KW energizes through ballast lamp 18 a solenoid C<SP>1</SP> closing the first contacts C/1 and second contacts C/2, C/3 the latter shunting the solenoids A<SP>1</SP>, B<SP>1</SP>. Subsequent operation of another switch 4KW passes current through a ballast lamp 16 and closed contacts C/2. Contacts C/1-C/3 open allowing the solenoid B<SP>1</SP> to be energized hence contacts B/1-B/3 close shunting the solenoids A<SP>1</SP> , C<SP>1</SP>. Contacts A/1-C/1 may be replaced by vacuum or mercury switches.