This paper presented some new experimental results observed in our investigation. Based on the experiments, it was found that the different voltage application sequence on the test samples could influence the flashover voltage of the tested samples. Three kinds of voltage application sequences were compared and three kinds of Alumina samples were involved in this paper. In general, the flashover voltage is the lowest if the applied voltage started from a lower voltage (-2kV) at a -2kV step; the flashover voltage could be the highest if the applied voltage started from -22kV. The surface charge distributions were observed after the voltage was applied. According to the experimental results, the change of the flashover voltage of the test samples could be attributed to the state of surface charge distribution with different voltage application sequence.

This paper has investigated the thermally stimulated current (TSC) of Alumina ceramics using a uniform electrode system. Experimental results with different Alumina ceramics showed that TSC characteristics of the samples prepared with varied metal oxide additives was different. The trap distribution parameters were calculated from TSC curves, the calculation results show that the additives significantly influence the trap distribution.

In this paper, the Influences of electrical field on boiling-condensation heft transfer system have been investigated using a cylinder beat transfer model Freon-ll is selected as working fluid. The condensation heat transfer coefficient, the boiling heat flux the saturation pressure are meassured in this investigation. According to the experimental results, it is found that the electrical field can influence best transfer system. The boiling heat transfer is enhanced by the applied voltage, and the saturate vapor of working fluid is condensed on the high voltage electrode directly when the applied voltage is higher than 6kv. The experimental results have been discussed, and it is considered that the high electrical field strength change the thermal properties of working fluid.

It was considered that the trap distribution of alumina ceramics could affect the flashover performance of insulators. This paper investigated the trap distribution of alumina ceramic samples with different additives and different sintering temperature respectively. Experimental results show that the additives and sintering temperature play an important role on the trap distribution of alumina ceramics respectively, especially on the trap energy distribution, and they affect the trap distribution of alumina ceramics significantly.

A measuring system for on-line detecting partial discharge of generators has been designed with the ultra high frequency (UHF) and high frequency (HF) method. It not only has the capability of calibrating the PD level, but also has the excellent ability of anti-interfering on site. The test data shows this technique is very promising.