GB519481A - Improved arrangement for controlling gas- or vapour-discharge tubes - Google Patents

Abstract

519,481. Control systems for consumption apparatus. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Oct. 18, 1938, No. 30182. Convention date, Oct. 21, 1937. [Class 38 (iv)] Thermionic control.-In a device for controlling vapour or gas - discharge tubes 4, 5, which, by means of an arrangement supplying alternating voltages are ignited successively, the alternating voltages are generated by current pulses in a circuit comprising the primary 11 of a transformer 8, in. which the passage of current during one half wave and in one direction can be controlled by a grid-controlled rectifier 15 whilst uncontrolled means comprising a rectifier 19 oppositely connected in parallel with rectifier 15, or an oscillatory circuit, including a separate winding on the primary of transformer 8, are provided to pass corresponding parts of the half - waves in the other direction, so that the ignition of the discharge paths occurs at a time interval of about 180 degrees or about 180 degrees. In the example the current for a seam-welding installation is taken from the secondary 2 of a mains transformer 3 and supplied to welding-electrodes 1 through gridcontrolled discharge vessels 4, 5 which are preferably oppositely connected in parallel. The control voltage produced by the rectifier 15 is applied to the grids 6, 7 through the secondary windings 9, 10 of transformer 8. The primary winding 11 of transformer 8 is in series with the secondary 12 of a transformer 13 and with the grid-controlled rectifier 15. The phase of the voltage applied to control grid 16 is adjusted suitably with respect to that of transformer 13 A second control grid' 17 may be provided for controlling the duration.of the impulses of the welding current and of the periods of rest. The non-controlled rectifier 19 is oppositely connected in parallel with the rectifier 15 and, by inserting a condenser 20 in the common supply conductor for the two vessels 15, 19, it can be ensured that the shape of the curve of the voltage set up at secondary windings 9, 10 approximately corresponds to the wave form of the alternating voltage of the transformer 13. If this latter wave form is symmetrical and, for example of pure sine shape, the main discharge tubes 4, 5 can be ignited 180 degrees or thereabouts after each other.