A Linear Model for the Differences of Breakdown Voltages in IEC 60052 Tables

IEC 60052 table 2 and table 3 provides the values of breakdown voltage for sphere gap occurred from different values of gap diameter and gap spacing. This document investigates the breakdown voltages from IEC 60052 table 2 and IEC 60052 table 3 under the same values of sphere gap diameter and gap spacing. The result shows that, provided the same condition of sphere gap diameter and gap spacing, the breakdown voltage value from table 3 (positive impulse) is higher than the breakdown voltage value from table 2 (negative impulse). Also, the relationship between the difference in breakdown voltage with diameter and spacing is simply a linear model in which a least square regression that minimizes sum of square errors can be used to find the relationship. With least square approach, a linear regression equation without an intercept term, or linear regression through the origin, is better accurate than the linear regression with an intercept term. The difference in breakdown voltage also reveals an incongruity in a step function pattern in the data in which an adjustment in removal of some data points was made to propose another regression through the origin equation the explain the difference in breakdown voltage to gap diameter and gap spacing.