Research on NOFRF Entropy-Based Detection Method for Early Damage of Pillar Porcelain Insulator

Table 6

Factor and level table of the test.

Level	Crack location (A)	Crack length (with fixed depth 5 mm) (mm) (B)	Angle of axial crack (°) (C)
1	Top flange	3	30
2	Insulator middle	5	60
3	Lower flange	15	90