Mohammad Hadi Zare - Faculty of Electrical and Computer Engineering, Yazd University, Yazd, Iran
Ahmad Mirzaei - Faculty of Electrical and Computer Engineering, Yazd University, Yazd, Iran

Ferroresonance phenomenon is likely in cable distribution systems particularly in ungrounded systems. The distortion amount of voltages and currents as well as overvoltages and overcurrents in the system are a function of system parameters such as phase to ground capacitance and transformer magnetic characteristic.In this paper a typical distribution system with three transformers having different core characteristics is considered and ferroresonance effect on measured voltages is studied for various conditions using Electro-Magnetic Transient Program (EMTP). Simulation results revealed that the severity of ferroresonance and voltage distortions in modern power transformers feature high inductance in their linear region and low core losses is more than conventional ones. The results also indicated that the total harmonic distortion of voltage during ferroresonance greatly depends on the system parameters

Ferroresonance, Voltage Measurement, Core Magnetic Characteristic, Total harmonic distortion