Selenium rectifiers — Factors in their application

Selection of the proper selenium rectifier stacks for best results in the design of dc power supplies involves consideration of characteristics not ordinarily found in published data. This paper describes the data required for the selection of selenium cell sizes and cell combinations, shows typical voltage-current characteristics, and gives the results of extensive life test data necessary for evaluating the life expectancy of the product. The life test data indicate that there are substantial differences in the life expectancy of selenium stacks as manufactured by various companies in this country. Shorter life can be anticipated as the rms cell voltage ratings arc increased. In addition, the life is affected by the current density and the temperature at which the selenium cells are operated.