Table 8: Fault diagnosis using Rogers ratio method.

Diagnosis

0000Normal aging
3000Partial discharge (corona)
1~2000Overheating (≤150°C)
1~2100Overheating (150°C~200°C)
0100Overheating (200°C~300°C)
0010Metal superheating
1010Circular current in coil
1020Circular current in iron core and shell or joint overload
0001Arc discharge-no perfoliate discharge
001~21Arc discharge-perfoliate discharge
0022Continuous discharge breakdowns
3001~2Partial discharge-corona (sign of creepage)