Abstract :
R. B. Williamson (by letter): This paper is of special interest to me because I happened to be responsible for the design of one of the 32,500-kv-a. units installed in this station in 1919, and also have had in charge the design of a 65,000-kv-a. unit which will be put in the same station alongside the unit described. At the time the 32,500-kv-a. units were started, they were the largest of their kind but they had been in operation but a short time before plans were made by The Niagara Falls Power Company to install three additional units of 65,000-kv-a. output. The three 32,500-kv-a. units have now been in operation for four years or more and have given excellent service. Further, these units showed a very high efficiency, 97.5 to 98 per cent, and the larger unit was not adopted with the expectation of securing any material gain in efficiency. Neither does the large generator cost appreciably less per kv-a. output, since the speed is lower and the weight per kv-a. somewhat higher. It may be repeated here, that the 32,500-kv-a. units operate at 150 r. p. m. as against 107 r. p. m. in the ease of the 65,000-kv-a. machine.
