GB376440A - Improvements in or relating to x-ray tubes and other thermionic or electron discharge devices - Google Patents

Abstract

376,440. R÷ntgen ray apparatus. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Kearsley, W. K.; 1606, Randolph Road, Schenectady, New York, U.S.A.) May 28, 1931, No. 15675. Convention date, May 28, 1930. [Class 39 (i).] X-ray tubes are protected against excess consumption by thermal switches which are so connected in circuit as to be heated proportionally to the heat of the anode and on a lower scale. As shown the thermal element 17. carries the current in the primary of the transformer 15 which supplies the current input to the tube. The effective part of the current input to operate the thermal element may be varied by the adjustable shunt-resistance 27. The voltage of the supply may be varied by the potentiometer tapping arrangement shown. In shunt across the applied voltage is a heating element 18 located near the thermal strip which is thus heated in accordance with a measure of the wattage input to the tube and may be designed to reproduce the thermal characteristics of the anode. The cathode 13 is supplied from a potential transformer 14. When the input is so great as to endanger the anode the thermal switch closes its contacts and energizes the breaker 22 to open the supply circuit which is reclosed when the thermal switch cools again.