Sixty-cycle calibration of the 50-centimeter sphere gap

ONE OF the important functions of the Institute is to provide specifications relating to the standardization of testing equipments and methods. Since the publication of AIEE Standards No. 4, May 1928, considerable progress has been made in the extension and revision of the calibrations for the grounded sphere gap for both 60-cycle and impulse voltages. This paper presents data which should be of assistance in establishing the calibrations of ungrounded sphere gaps. In addition to these data, the paper also describes the equipment and method used in determining the crest voltage applied to the spheres and the means of determining the spacing at spark-over. Data are also presented upon the effect of ultraviolet irradiation of the spheres.