Electromagnetic processes in power transformer windings during typical pulse testing
Resonance voltage of one of the natural resonant frequency progresses in power transformer windings when they are under the influence of pulse overvoltage. The amplitude of free oscillating voltage and the amplitude of the pulse voltage are commensurable, but the existence time of oscillation lasts tenfold longer than the existence time of pulse voltage does. The overvoltage may cause coil faults. Overvoltage limiter installation is the main issue of reliability improvement in 110 kV or less power supply system.