The results from two series of test have been analysis for comparison the effect of excitation. Figure 29 shows the LC which summarized within four days with various cycles. On the first 100 cycles, both of LC obtained from two excitation voltage types gradually increases almost the same trend and less than 1 mA on wet condition. In this period, the LC is not sufficient enough to aging surface and the saline resistance layer has not yet been formed completely. However, the LC rapidly increases during 100 - 350 cycles. The peak amplitude of LC occurs at the initial excited voltage and rapidly decreases after 5 seconds. This phenomenon occurs due to thin pollution layer has been dried rapidly causes by heat which generates by LC. In this condition, it presents a low surface resistance on wet condition. After 450 cycles the LC gradually increases but duration of the peak LC is longer than 20 seconds. In this period, the longer LC caused by accumulation of saline on surface have been formed completely thickness conductivity layer. Furthermore, the results show different effects on excitation voltage after 315 cycles. It might be contributed by the impulse effect. The partial discharge at dry band of insulator has been occurred during excitation HV voltage when the LC exceeds over 1 mA.