Loading of Power Transformers

Most of the power utilities in the country do not allow the load on the power transformers to exceed the name-plate rating and restrictions of load are imposed as and when it exceeds the transformer rating. An assessment about the actual use of life of most heavily loaded transformers installed at a few important sub-stations in the B.B.M.B. System was made and it was found that the actual rate of utilisation of transformer life is very low. Due to this low rate of utilisation of transformer life, it is possible to meet the short time peak load requirement even beyond name-plate rating from existing transformers without consuming more than their normal life. Following advantages can be derived by proper utilisation of the loading capability of the power transformers : (i) It will help planners in choosing appropriate ratings of transformers, (ii) Future augmentations can be deferred or reduced, (iii) Switching off of feeders during peak load hours when load exceeds transformer name-plate rating can be avoided in most cases, and (iv) Saving in additional core losses during lean periods.