Transformer Technology Tech Talks – Khayakazi Dioka, Eskom

Most utilities replace transformers when they get old. Eskom replaces them when they get sick. And that distinction is saving one of the world’s largest fleets from premature retirement.

In this Transformer Technology profile, Editor-in-Chief Alan Ross sits down with Khayakazi Dioka, Senior Transformer Engineer at Eskom, to unpack how South Africa’s national utility manages over 400,000 transformers across transmission and distribution, and why age has nothing to do with replacement decisions.

With responsibility spanning everything from 2.5 MVA distribution units to 800 MVA power transformers, Dioka walks through the Asset Health Appraisal system that prioritizes every transformer in the Eskom fleet by condition, not chronology. The conversation covers DGA trending, insulation life assessment, online gas analyzers, and the one component that can turn a perfectly healthy transformer into a fireball overnight.

What you’ll learn in this profile:

• How Eskom’s Asset Health Appraisal evaluates over 600 transmission transformers and 5,000+ distribution transformers every 2 to 3 years
• Why a 200 DP reading signals end of life, and why Eskom still keeps those transformers in service
• The economics of monitoring: what makes sense on an 800 MVA unit versus a pole-mounted transformer
• How DGA trending catches developing faults that online gas analyzers can miss
• The bushing that costs a fraction of the transformer but can destroy the entire unit
• Eskom’s 5-year shift from age-based to condition-based replacement, and the database infrastructure behind it
• Manual oil sampling every 6 months vs. real-time online monitoring: when each approach wins
• The weighting formula that gives insulation condition more influence than gassing in the asset health score

Guest: Khayakazi Dioka, Senior Transformer Engineer, Eskom
Host: Alan Ross, Editor-in-Chief, Transformer Technology