Chaos in ferroresonant wound voltagetransformers: effect of corelosses and universal circuit behaviour

The damping effects of transformer core losses upon the ferroresonant behaviour of wound instrument transformers, fed from a sinusoidal supply through circuit breaker grading capacitance, are studied using nonlinear dynamical methods. The system is shown to exhibit three types of ferroresonance; fundamental frequency ferroresonance, subharmonic ferroresonance and chaotic ferroresonance. It is also shown that this ferroresonant circuit can be driven into chaotic behaviour through a sequence of period-doubling bifurcations. Values of Feigenbaum universal number δ are calculated and are shown to be in good agreement with those reported from various other disciplines.