Improvements of high accuracy AC dissipation current waveform observation system

Nonpolar polymers, such as polyethylene, polypropylene, are widely used as the insulation materials for power cables and power capacitor. It is very important to know high field AC conduction mechanisms for designing the high performance insulator. In our previous study, dissipation current under AC high field utilizing Capacitance Bridge was developed. As the results of these experiments, possibility of space charge effect under AC high field is pointed out and reported. Normally, under AC high field and in high temperature, the dissipation current becomes nonlinear property. To study space charge effect, it is important to measure harmonics of dissipation current with high accuracy. Then, it is developed new dissipation current observation method, which makes possible to measure harmonics with high accuracy. In this paper, the improvement of this new measuring system is discussed