Effect of load factor on operation of power transformers by temperature

L. W. Clark (The Detroit Edison Company, Detroit, Mich.): Mr. Montsinger proposes a rule of allowing 3 per cent increased load for each 10 per cent that the daily load factor falls below 100 per cent. We believe that this rule is conservative if load factor is used as a basis but, in our opinion, load factor alone is not a suitable measure upon which to base permissible loading. As pointed out by Mr. Montsinger, the permissible load may actually vary over a wide range, depending upon the shape of the load curves, and yet the load factor of these curves may have the same numerical value.