Thermal capability assessment for transformers

The reliability of transmission and distribution equipment is inevitably affected by service conditions, and particularly loading, e.g. average load, load variation, loading above nameplate rating and frequency of tap-changes. The ability of a transformer to cope with particular loading conditions will depend on the design involved. An important aspect of this design is the thermal capability of the windings. This paper describes how the National Grid Company (NGC) maximises the thermal capabilities of its transformers without sacrificing reliability by using a transformer thermal monitor and the TEFLOW2 computer program