Voltage transformer ferroresonance in 275 kV substation

The ferroresonant behaviour of a 275 kV electromagnetic voltage transformers, fed from a sinusoidal supply via circuit breaker grading capacitance, in a National Grid substation in analysed using nonlinear bifurcation diagrams representing system behaviour have been presented showing two possible types of operation, normal response and fundamental frequency ferroresonance, in line with practical site experience.