GB215372A - Improvements in circuit arrangements employing vacuum tubes - Google Patents

Abstract

215,372. British Thomson-Houston Co., Ltd., (Assignees of Prince, D. C.). May 4, 1923, [Convention date. Addition to 206,837. Thermionic generators. - The arrangement for generating polyphase alternating or oscillatory current described in the parent Specification is provided with modified means for securing a lead of the grid potential relatively to the potential of the corresponding plate secondary winding; and for automatically varying the angle of this lead in accordance with the load supplied. The valve circuits are the same as those shown in Fig. 3 of the parent Specification, the primary coils 4, 5, 6 of a three-phase transformer being connected in the plate circuits of three valves, and the secondary coils 18, 19, 20 of a second transformer being connected in the corresponding grid circuits. The secondary coils 9, 10, 11 of the plate transformer are connected by means of tappings 32 to series inductances 29, 30, 31 in the output leads 12, 13, 14 and the primary coils 15, 16, 17 are connected to other tappings 33 on the same inductances, as shown in Fig. 2. By this means an adjustable phase difference is obtained between the grid potentials and the potential of the corresponding plate circuit secondary, and the amount of this phase difference varies automatically with the load. Alternatively as shown in Fig. 3, the leads from the grid transformer primary 15, 16, 17 may each include a pair of coils coupled to two of the coils 29, 30, 31, and may be taken to tappings on the secondary coils 9, 10, 11 of the plate transformer. In a further modification, shown in Fig. 4, separate primary coils 43, 44, 45 are provided for the grid transformer, and each coil is connected in series with an inductance 46, 47, 48 between one of the output leads 12, 13, 14 and a tapping 26, 27, 28 on one of the adjacent coils 9, 10, 11.