Substation power-transformer-loading analysis and computer simulations of loadability under realistic operating conditions

Transformer loading analyses and computer simulations of transformer thermal behaviour under realistic/typical operating conditions (loading and ambient-temperature profiles) indicate that substation (DS) power transformers in Ontario Hydro can be loaded to 1.8-1.9 p.u. Of the ratings during annual (winter) peak load periods without sacrifice of normal transformer life expectancy or reliability of supply to achieve the goal of making the best use of transformer capabilities. Adoption of the proposed increases in loading limits will result in a significant cost saving for Ontario Hydro, estimated at $4,500,000 (NPV 1991 Canadian dollars) over three years (of a reduction of $10,000,000 per year on DS capital cost)