Economics of System Conversion from 27.6- to 33-Kv Operation

The South Bend division of the Indiana & Michigan Electric Company (I&ME) is served by a 27.6-kv subtransmission system and is the only area in the entire American Gas and Electric Company (AGE) system operating at this voltage. Realizing that future conversion of this area to 33-kv operation, standard throughout the remainder of I&ME, would be desirable, all new transformers have been purchased in the past 10 years with taps suitable for both 27.6 and 33 kv. In this way gradual replacement of transformers would result eventually in a system which, with only minor equipment modifications and changes, could be converted readily to the higher voltage. A review of this approach recently was undertaken in an attempt to determine if immediate conversion could not be justified. As part of this investigation, an economic study was made. Monetary benefits anticipated from operation at the higher voltage were compared, by a present-worth evaluation, with the investment necessary for conversion, and the project was found to be economically sound. On the basis of this over-all review, it was decided to proceed immediately with complete conversion.