Transformer Design by Computer

Abstract

The blending of traditional transformer design practice with the phenomenal speed and logic adaptability of a modem computer has lead to a greater insight into transformer design procedures. This is due in part to the ability of the computer to execute many cumbersome and reiterative calculations in a logical and stepwise procedure leading to a design that satisfies ail input specifications. Several empirical relationships are used to provide a good starting point in a generalized design procedure as well as the means to handle subsequent changes. In addition, the interaction of temperature rise, voltage regulation, and losses upon the various parameters is analyzed and treated in a logical order to achieve the design objective. One of the innovative features of the computer program is the user's option to examine the nature of the variation of nine key parameters of interim designs that the computer prints out as it successfully approaches the final acceptable design. In this way, unusual input requirements may be discovered. If required, changes may be inserted into the input specification, and then the process can be continued until an acceptable design is reached. The scope of this computer program covers single-phase and three-phase power transformers from 1 to 5000 W and utilizes 13 different kinds of magnetic steel. In addition, there is no limitation as to the number of primary and secondary windings and taps on any winding. Concurrent to the transformer design program is a cost analysis program, which may be used independently if needed. The cost program develops material costs in detail and a labor analysis that sets forth a detailed list of labor operations necessary to construct the transformer being analyzed. Material costs are listed in the form of a parts list. Labor costs are summarized by listing all the required operations in units of time; likewise the setup is listed where it is required and tooling if it is necessary. Total labor cost is obtained by using an established average labor rate. The cost program is flexible in that it accommodates the most usual transformer structures, which include open as well as hermetically sealed units.