Application ratings of indoor power circuit breakers

Increased cost involved in serving electric power to customers, and the aim to lower rates, have accelerated the need for most efficient utilization of existing generating and distribution equipment. The paper describes a method for loading power circuit breakers on a temperature basis for the purpose of taking advantage of their inherent current carrying ability. Several years of practical application of the basic theory has proved entirely satisfactory on various types of electric equipment and has, in many cases, established considerable savings on new investments. While these savings apply to a lesser degree to circuit breakers than to other major power equipment, their application in accordance with temperature, rather than name plate rating, has put the use of new and existing facilities on an equally sound engineering basis.