Failure Analysis and Investigation of Electrical Insulation of 10 MVA Oil-Type Transformers Damaged due to Direct Lightning Strikes

Failures in distribution transformers are associated with high property damage, high business interruption losses and large insurance deductibles. Professional independent inspection and protection design, taken on an ongoing basis, can go a long way towards reducing failures and eliminating unnecessary repair costs. This paper presents the study of the effects of lightning on electrical insulation, damage, and components in and components in 10MVA, 24/6.6kV oil-type transformers. Beginning to investigate and diagnose the cause of the transformer explosion by measuring electrical parameters to confirm which parts have been damaged. The result of the measurement shows that there is a fault in the HV coil. The investigation method focuses on the damage and solutions to prevent the problem from occurring again. Finally, a lightning protection design is necessary.