In this paper

it is found through analysis of two continuous fault of series reactor（with dry-type air-core） at certain power-converting station that the direct reason causing such two faults is the production process defects existed in the earlier stage in manufacturing procedure of the reactor. Uneven potential distribution of reactor is caused by the lateral penetrating crack occurred on many places of envelopment after rain entering into the crack.The partial discharge happened at the defect places

causing inter-turn short circuit.And the preventive measures and suggestions are put forward.