Page 74 - Energize October 2022

TECHNICAL

Conclusions of warranty failure. As one example, National Grid (UK) has
Fault and failure investigations on power transformer components reported, “A number of faults have been detected, although in
have an important role in improving reliability and managing the each case the transformer had satisfactorily passed the routine
risk of transformer failure. The identification of the primary cause tests”
of failure and the subsequent analysis enables recommendations CIGRE report 1984 states that “Dissolved-gas-in oil
for corrective action to be made that hopefully will prevent chromatographic is successfully applied to fault detection in the
similar failures from occurring in the future. maintenance of large power transformers. Savings which could be
When design error and/or weaknesses developing over time achieved are in the region of hundreds of millions of US dollars.
are uncovered, enhanced monitoring/investigation on sister units Independent professionals and consultants are only able to
built by the same manufacturer will help in preventing future offer their opinions.
failures and therefore aid in managing the risk of unexpected Experience and understanding of the diagnostic methods are
failure. required to make DGA a more exact science and not an art.
Transformer manufacturers need to balance the cost of
equipment with reliability. Acknowledgements
The transformer problems at the Hillside smelter fit the Bath The author thanks and acknowledges the following people for
Tub Life Cycle Model. their contributions: Sunny Sujan, BHP Billition, Luwdren Moodley,
The application of DGA was 100% successful in identifying the Doble Engineering Africa and Piet Goosen, Corporate Consultant
faults at early life. DGA oil testing is typically a critical first step in (Power Equipment), Eskom
any power transformer analysis.
The DGA technique detects newly formed faults both This article was presented to EuroTechcon 2011. The unabridged
accurately and consistently and will locate a fault that cannot be version can be found at: https://oilwatch.co.za/dissolved-gas-
detected in any other way. When abnormal gassing patterns have analysis-at-an-aluminium-smelter/
been established the unit should be removed from service as
soon as it is practically possible. Contact Oilwatch, Phone +27 87 238-2188,
Document first year in-warranty problems before out support@oilwatch.co.za, www.oilwatch.co.za