Disruptive strength with transient voltages

Experience with high voltage transmissions and distributions shows that high frequency oscillations and other disturbances of limited power do not exert as high a disruptive effect, at least on oil and solid insulation, as should be expected from their voltage. Discharges have been observed between the terminals of high-potential oil transformers through the air, which require voltages far beyond those which the transformer insulation could stand, and the absence of a break-down of the transformer could not always be explained by the screening effect of the reactance of the transformer leads.