Design of sealed ignitron rectifiers for three-wife service

Abstract

I N the past four years, the many con structional and operational advan tages of sealed ignitron rectifiers have greatly aided the war effort by saving critical materials and manufacturing fa cilities. Two-wire sealed ignitron rectifi ers 1 have met industry's urgent need for efficient d-c power and have found wide" application in the range of 75-to 1,000-kw capacity, at voltages ranging between 250 and 600 volts direct current for general in dustrial, railway, mining, and-electro chemical service.The field of application of the ignitron rectifier is considerably enlarged by the introduction of equipments for threewire service, and it is the purpose of this paper to describe the design, character istics, and performance of these units. The Field for the Three-Wire RectifierOne field of usefulness of the three-wire rectifier is for supplying d-c power to in dustrial three-wire systems. There is an other application to be found in metro politan districts where steps are being taken to retire the Edison three-wire d-c system and existing building generating plants. In many cases it will not be eco nomical to rewire buildings for a 208-volt three-phase 60-cycle supply or to replace d-c motors and control for a-c operation. The problem of supplying d-c power for three-wire systems without the installation of rotating apparatus has long delayed the conversion in many districts.Three-wire sealed ignitron rectifiers offer several distinct advantages when compared with other forms of converting equipment. The rectifier is largely static, thus eliminating special foundation and space requirements. Rectifiers are quiet in operation and easy to operate. The noload losses are small and the efficiency is fairly constant and reasonably high over the entire load range. Rectifier equip ments are factory assembled as unit d-c substations thereby minimizing installa tion time and expense.