Carrying Capacity of 60-Cycle Busses for Heavy Currents

Up to the present time it has seldom been necessary to design busses for carrying capacity above 2000 or 3000 amperes. Within the last few years we have passed this mark, and we shall soon be required to design busses for very much larger capacities. For simple geometrical designs there are formulas from which we may calculate the capacities of large busses. These simple designs cannot be easily mounted, and for this reason we must resort to styles which are easier to construct. These types cannot be calculated readily by the mathematics available to the ordinary engineer. This paper is presented with the idea of giving a ready reference for determining bus capacities without involved calculatwns. Curves are given showing the carrying capacity of a few types which are proposed as standards, and, in addition, a few curves compiled from tests showing the distribution of current in busses to show the necessity of this type of design. By a little careful study of these curves, the average designer may quickly choose the type of bus which will best meet his requirements for carrying capacity and allowable space. All busses are designed on the basis of 30-deg. cent. temperature rise, and their ratings may be proportionately increased if the conditions warrant a 40-deg. temperature rise.