The characteristic parameters of PT are calculated by processing the test data in the least squares curve fitting methods. Based on equivalent model of PT

this paper analyzes the reduced equivalent circuits to the power system with earthed and non-earthed neutral respectively. The act of PT core loss on damping ferroresonance intensity and persistence is proved theoretically. The simulating tool of MATLAB is then applied to calculate the effects in both systems

which are caused by changing core loss of PT at different condition of ferroresonance. From the results

it is shown that the influence exists under all of the conditions and is more remarkable in the earthed neutral power system. The lower the core loss is

the intenser the resonance is

the higher the value of overvoltage caused is. The results are in good agreement with the analysis concluded in theory. It is also helpful to design suitable equipment for suppressing resonance in different types of power system.