Correction procedures for high-voltage measurements under a variable air density

Recent discussions relating to both the IEC and IEEE procedures for the adjustment of measurement of high voltages to a common atmospheric density make it desirable to compare the relative merits of the procedures IEC 60-1 (1973) and IEC 60060-1 (1989) both of which are in use for this purpose. The present discussion is divided into sections concerned with long air gaps between electrodes (>1 m), short air gaps (<1 m) and gaps containing insulators. Problems arising with direct and alternating voltages are included. It is shown that for simple long air gaps, the 1973 and 1989 procedures are of comparable precision. However, the 1989 procedure explicitly takes into account variations of leader growth due to impulse rise time and length of gap, and may therefore be considered more satisfactory than the 1973 procedure. Neither procedure is satisfactory for gaps <0.5 m