GB398377A - Improvements in or relating to electron discharge timing devices - Google Patents

Abstract

398,377. Control systems for consuming-devices. IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London.- (Assignees of Stansbury, C. and Brown, G. C. ; N. 12th Street, Milwaukee, Wisconsin, U.S.A.) Dec. 9, 1932, No. 34962. Convention date, Dec. 10, 1931. Addition to 370,002. [Class 38 (iv).] In the thermionic time-delay device described in the parent Specification in order to prevent the reclosure of the controlled circuit by the reclosing of the control switch before the requisite time delay period has fully elapsed, the discharge circuit of the grid control condenser is completed by a relay the operation of which is independent of the control switch. As shown in the Figure applied to an electric welding plant the relay 10 has its coil 11 in the anode circuit of the valve 15 and is normally energized by plate current through the valve the discharge circuit for the grid condenser being broken at contacts 14. When the control switch 5 is opened the change in potential of the grid due to the insertion of the resistance 21 in series with resistances 22, 20 across the supply L<1>, L<2> causes a cessation of plate current in the valve 15 and the discharge circuit of condenser 19 through resistance 23 is completed at contacts 14. The opening of contacts 13 thus renders any subsequent reclosure of the control switch 5 ineffective during the time period which elapses until the valve again becomes conducting when the relay 10 is again energized and the welding circuit 3, 4 is broken by de-energization of relay 6 controlling the primary circuit 2.