Voltage linearity of scale factor and wave shape parameters of UHV impulse voltage dividers

Determining the voltage linearity of a large impulse voltage divider used in the testing of ultra-high-voltage (UHV) equipment is a challenging task. This leads to the question of whether the uncertainty requirements, specified in the present edition of IEC60060 [1, 2], can be met in the UHV range. This paper presents the results of voltage divider linearity tests at voltages up to 2400 kV. Measurements of the voltage linearity of the divider scale factor (or peak voltage), as well as the voltage linearity of the time parameters, are presented. Methods for calculating the linearity values and their interpretation are discussed. It is concluded that achieving voltage linearity of less than 3% for scale factor and voltage linearity of less than 5% for time parameters may be difficult for dividers used for testing in the UHV range. Other voltage linearity methods should be studied in order to appropriately specify measurement uncertainties for impulse testing in the UHV range.