Development of excitron-type rectifier

METAL-TANK mercury-arc rectifiers have been in commercial use abroad since 1911, and in the United States since 1925. (There were several earlier experimental installations in this country, in 1913 and 1915.) Until recent years, all rectifiers were of the multianode type, with 6, 12, and 18 anodes in one tank. The trend had been to increase the number of anodes per tank to obtain a higher current rating per rectifier, and in Europe rectifiers with 24 anodes in one tank were developed. This trend was reversed in the United States with the introduction of the single-anode ignitron-type rectifier. The single-anode rectifiers are assembled in groups of 6 or 12 to make up one unit.