Forensic Investigation to find common Cause Failure Modes

K-BIK Power was bought in to do a forensic investigation of two transformer failures after the Client had had more than four units fail in only 2 years. The processing plant was less than 10 years old and had a large fleet of medium to large distribution transformers all from the same manufacturer.

The electrical test results showed some small changes that were still within the normal test result tolerances but had worsened over the previous 2 sets of results.

Key Challenges

The Client’s own investigations were limited as they did not have the experience to study the transformer internals.

Their DGA results showed some transformers with normal gas tendencies and some with abnormal tendencies, but the failures did not appear to align with the gas results.

K-BIK Power’s Approach

K-BIK Power was recommended to the Client and was subsequently engaged to undertake a full forensic investigation into two of the failures.

The gas results were plotted in the K-BIK Power diagnostic tool and showed there were some common markers that each transformer had well before the failures.

The electrical test results from the units prior to their failures did not show any abnormalities.

The transformers were opened and the internals stripped down to study the location of the failures.

Whilst the locations were slightly different in the two units inspected the failure mode was identical. When comparing back to the DGA results the markers noted were likely very early warning signs that the issue was developing. 

The markers were not clear to someone without detailed experience and so can go undiagnosed until the failure occurs.

Solutions Delivered

K-BIK Power found the failures were common across all the failures at the site and that several other transformers had similar markers present.

The common fault could not be repaired without extensive and costly factory-based work being done.

The Client was able to implement a strategy to manage the transformers at greatest risk of failure until new transformers could be delivered and changed out. This has helped prevent more failures and lost production for the Client.