Meeting of the American Institute of Electrical Copyright, 1912. By A.I.E.E. SOME FEATURES OF THE OUTDOOR ELECTRICAL INSTALLATION BY F. C. GREEN Economy in the construction and operation of power systems is engaging the best thought of engineers with the purpose of making the systems attractive to investors, as well as to those who utilize the power. The outdoor installation is based principally on economy in construction and partly on economy in operation. The presentation of a previous paper' on this subject was the occasion of much discussion by eminent engineers. Many of the details of construction and operation were gone into. The idea was indorsed by some and opposed by others, while in the main the discussion was mildly favorable. It was generally agreed that the principal consideration is economy. Some careful figures made for small substations show a net saving of 10 to 30 per cent over the indoor installation. At that time the outdoor installation was limited to transformers of small capacity except some 500 kv-a. 60,000-volt transformers that had just been installed. According to the general opinion expressed, the principal difficulty was to prevent moisture from getting into the outdoor transformers and switches. The extra cost of making them water-proof and air-proof was estimated to be from 6 per cent to 8 per cent. There was some difference of opinion as to whether life and property hazard, and convenience of operation would be seriously different from these features of indoor stations. Most of the discussion was based 1. High-Voltage Transformers and Protective and Controlling Apparatus for Outdoor Installation, by K. C. Randall, TRANSACTIONS A. I. E. E. 1909, XXVIII, I, page 189. upon more or less apparently well grounded opinion, practically no experience being given. List of Transformers. Following are the ratings of some transformers built for outdoor operation, since the presentation and discussion of the 1909 paper: In numerous transmission systems, high-tension oil switches and lightning arresters are installed outside. In several substations, transformers, as well as high-tension and low tensionbuses, are outdoors. TYPES OF INDOOR CONSTRUCTION Thus we find the extensiveness with which the idea is being put into practise, warrants further consideration of the advantages and disadvantages involved. A study of the principal factors of economy seems to lead to the conclusion that a greater percentage of saving may be expected than the values given in the previous paper and its discussion; and that the idea may be profitably extended to the installation of oil switches, buses and transformers outdoors for both substations and power stations, FIG. 1-SHOWING CONSTRUCTION OF GENERATOR BUS COMPARTMENTS FIG. 2-OUTDOOR INSTALLATION OF OIL SWITCHES AND BUSES FOR 100,000-VOLT SERVICE |