Table 3.

Variation of IDM of surface discharge images during AC flashover process.

Stages	0°	45°	90°	135°
Stage I	0.9895	0.989	0.9895	0.989
Stage II	0.9791	0.978	0.9843	0.978
Stage III	0.9584	0.9617	0.9635	0.9562
Stage IV	0.8781	0.8822	0.9077	0.8669
Stage V	0.8152	0.811	0.8345	0.7914
Stage VI	0.7821	0.7666	0.8103	0.7617
Stage VII	0.7273	0.7141	0.7682	0.7094
Stage VIII	0.2698	0.2415	0.3091	0.2405