Union station, a similar system to that operated by the New York Edison Company. In the magnificent Waterside station of this latter company, there are at present eleven 5,500-H. P. vertical engines, each driving a 4,500-K. W. three shows a row of rotary converters of a substation located in the basement of a sky-scraper in the heart of the business district of Chicago. The switchboard of a combined rotary converter and battery substation is shown in Fig. 31; the rear view, in Fig. 32. Where the load connected to transmission lines consists solely of substation converting apparatus, a low frequency is desirable because of the accompanying low inductive and capacity reactance of the lines, and also because of the slower speed of the synchronous motors and rotary converters which is had for a given number of field poles with a lower frequency. The higher the frequency, the greater the number of poles required, or the greater the speed. Because of the necessary number of commutator bars required between the brushes of a D. C. machine, and therefore also on a rotary converter, the distance between the centers of the pole pieces (that is, the pole "pitch") cannot be less than a certain FIG. 26. A 500-VOLT 2-PHASE GENERATOR. phase 25-cycle 6,600-volt alternator. A 5,000-K. W. Curtis turbo-generator is being installed, and there is room for four more. This will make a total rated capacity of 75,000 K. W., all power being generated as alternating current for transmission to rotary converter substations, from which it will feed into the Edison three-wire direct-current system. In the splendid new Fisk Street station in Chicago, 9,000-volt 25-cycle threephase current only is generated, all by Curtis turbo-generators. In Fig. 28 is shown a 5,000-K. W. Curtis turbine with generator; and Fig. 29 shows a Westing house-Parsons unit of the same capacity. In Philadelphia the 5.500-volt twophase 60-cycle system, already referred to, is used for transmission to rotary converter substations, as well as for the alternating-current distribution. Fig. 30 FIG. 28. A 5,000-K. W. CURTIS TURBO-ALTERNATOR. fixed limit; and therefore, for a given. speed, the lower frequency requires a far simpler and cheaper construction. The higher-frequency machines are also more liable to "hunt," especially when the load varies considerably. Furthermore, double-current generators having a commutator connected to the armature wind FIG. 27. A 3,500-K. W. ALTERNATING-CURRENT GENERATOR, HARRISON STREET STATION. ators, producing both direct and alternating current at the same time, form a very valuable element in a large station in which both these currents are generated, the direct current for general distribution, and the alternating current for transmission to substations. A frequency of 25 cycles is therefore generally accepted as the most desirable for straight the alternating distribution, as distinguished from transmission to substations, is effected by 60-cycle current. The 25cycle transmission current is then converted to current of 60 cycles per second by means of motor generators or straight frequency-changer sets. In Fig. 33 is shown such a motor-generator substation. The small units in the FIG. 32. REAR OF SWITCHBOARD OF ROTARY CONVERTER AND BATTERY SUBSTATION. tension switches for the substation are controlled from the switchboard, and are located in the basement, with the hightension busses. The switches are of the oil-well type, in which the circuit is opened in oil to prevent arcing with its often disastrous results. In Europe a compromise frequency of 42 and sometimes 50 cycles is common; and current is transmitted and distributed at this frequency, thus requiring only voltage transformers and no frequency changers. A few 25-cycle FIG. 30. ROTARY CONVERTERS INSTALLED IN SUBSTATION IN BASEMENT OF OFFICE BUILDING. FIG. 31. SWITCHBOARD OF ROTARY CONVERTER AND BATTERY SUBSTATION. constant-potential arc lamps. What this new system meant to the neighborhood in which the old stations were located, will be appreciated when one remembers the noise and dirt and smoke of these old stations, and then views Fig. 34, a substation set in the rear of a lot in a fine residence section. We have seen, then, how the highvoltage polyphase system has been evolved out of, and has unified, the mixed systems which were brought under one head during the era of consolidation. A study of some of the newest installations leads to the thought that perfection of system has almost been reached, and that further progress will be rather along the line of higher efficiency of apparatus at both ends of the system. When the true electrical era has arrived, when houses no longer have need of chimneys and all operations are performed electrically, then new problems will arise. How they will be met, none can now say; but they will be met successfully. Another Edison many of them, perhaps — will FIG. 34. MODERN LIGHTING AND POWER SUBSTATION. arise; and then our splendid systems of to-day may ultimately be supplanted by one of which the most imaginative. dreamer as yet has seen no vision. A BRAND NEW PASSENGER LOCOMOTIVE. Balanced-Compound-Vauclain System, with DeGlenn arrangement for transmitting power to axle. Built for the Chicago, Burlington & Quincy Railroad. be termed to coin a word for such railroad phenomena. The modern locomotive costs $15,000 or $18,000, according to size and equipment. Passenger locomotives in former days were embellished with extra brasswork and trimmings; the bright parts were kept by the firemen in a state of glittering effulgence; and the passenger engine cost more than the freight engine. Nowadays the trimmings are not put on; and the passenger engine, being lighter, costs less than the mammoth freighter. Reprinted from The Chautauquan. get all the service possible out of them. The age of expectancy is only approximate. Bad water-that is, water bad for the internal economy of boilers— which causes scale, is perhaps the greatest foe to an engine's hope for an honorable old age. A bad water division uses up its motive power far more rapidly than hard work elsewhere. Local conditions on the line largely affect the motive power. A hilly country causes more strain. Then too, housing facilities have much to do with the life of an engine. If it is possible to keep up with needs in repairs, the machine stands a better chance for giving long service. |