Effects of very fast transient overvoltages on transformer

An analytical solution is found using the Laplace transform to describe the very fast transient overvoltage (VFTO) in the gas insulated switchgear (GIS) connected directly to a transformer. The oscillation frequencies, and other properties, are explicitly given in terms of system parameters. The magnitude of VFTO at the transformer is suppressed due to the transformer capacitance. Magnitudes of the initial abrupt voltage change and oscillatory voltage are assessed. The abrupt voltage is larger, but not enough to induce a harmful voltage in the transformer. The oscillatory components may damage the winding insulation at the occurrence of resonance.