Discussion on “synchronous converters and motor-generators”

I am very glad to see that motor-generators are beginning to get their due. When synchronous converters were first brought out their theoretical and apparent advantages were so great that too much attention was paid to them and it has taken us a long time to recognize the very great advantages that motor-generators possess. The relative costs that have been pointed out by Mr. Waters to-day, and which were also pointed out by Mr. Eglin in a paper before the St. Louis Congress, and by Mr. Stott and others, are having the effect of drawing more attention to the availability of motor-generators. As I look at the tables on page 769 and especially with reference to the 500-kw., 600-volts, 60-cycles comparison, I see the motor-generator, costing under those conditions only 5 per cent. more. I would like very much if Mr. Waters would define what he means by the word “cost” in this table. There are so many things that may be included or excluded that the simple word alone does not give any information. He speaks of the motor-generator costing 20 per cent. more than the synchronous converter. Does that include any regulating device for the synchronous converter, also does it apply to machines set up or simply f.o.b. at the station; also are both machines three-phase?