GB396802A - Improvements in and relating to mercury arc rectifiers - Google Patents

Abstract

396,802. Transformers ; mercury-arc rectifiers. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, and READ, J. C., The Gable House, Bilton, Rugby. Feb. 12, 1932, No. 4250. [Class 38 (ii).] To enable the transformer normally used for supporting power current to a mercury arc rectifier to supply current at low voltage during the " bakeout " process for removing occluded gases, the secondary phase windings are changed to a series connection that would, with the same transformation ratio for each phase, produce no resultant voltage, and the tap connections are then changed so as to produce slightly unequal transformation ratios for the different phases thus producing a low resultant voltage for supplying " bakeout " current to the anodes. Fig. 2 indicates how the standard doublestar connection shown in Fig. 1 is changed to supply current at low voltage between the points 9, 10 and 11, 12 to two anodes. Fig. 6 indicates how the standard triple-star connection of secondary windings shown in Fig. 5 is changed to supply low-voltage current to two anodes, the tap connections on the primary side being changed as in the previous example. Where a connection involving two groups of secondary phases energized by separate primary groups is employed, corresponding phases of the secondary groups are connected in opposition and the tap connections are adjusted to give slightly different ratios so as to provide a low resultant voltage.