Abstract :
The design of electrical machines has two main aspects: firstly to fulfil a set of performance conditions, and secondly to do this at an economical cost. The relatively complex structure of the rotating machine with its large number of seemingly independent variables, as compared with that of transformers, has apparently discouraged basic attempts at determining an economical design. The following investigation shows, however, that definite functional relations between the design parameters can be established, and that all possible designs fulfilling certain basic conditions can be represented by a system of functions, which can be graphically treated, with the result of showing not only the economical optima but also the penalties that have to be paid in material costs for deviation from these optimal designs, and that are necessary to fulfil any side conditions that may be imposed on the design. The influence of the assumption of loading constants is examined. The simplicity of the equations arrived at makes it possible to investigate the economical effect of choice of stator outside and bore diameter and their ratios, and the effect of more than one rating based on the same laminations.
