Transients during the switching of SF6-insulated isolating switches

The transients produced by SF6 insulated isolators being switched were measured using wide-band voltage dividers, and the effect of the test circuit parameters on these transients was determined. The above was used to assess the maximum voltages with respect to earth, which the switchgear insulation has to withstand. The maximum overvoltage factor, which is defined as the ratio of the peak overvoltage to earth to the peak power frequency voltage, was found to be only 1.68. The transients were calculated in parallel with the measurements. A comparison of the results show that the equivalent circuits on which the calculation was based gave a relatively good description of the basic phenomena.