B. PD Pattern testing in each insulator
[1] Air Insulator with Tested Voltage at 6.0 kV This testing is applied the AC high voltage at 6.0 kV into the electrode. The gap length of electrode is 10 mm by using air insulator. Fig. 7, Fig. 8 and Fig. 9 show PD pattern of symmetrical shape, semi-symmetrical shape and unsymmetrical, respectively. The PD value of unsymmetrical shape is highest (5.5 pC) compared to other.