Some Large Trantformers.

Some Large Trantformers.

The Pennsylvania Water & Power Company generates power from the Susquehanna river at McCall’s Ferry, Lancaster county, where it will have an ultimate capacity estimated at 100,000 kilowatts. At present, the power generated is transmitted 49 miles to Baltimore, and transmission lines to other large cities, of which there are a number within economical transmission distance, are contemplated. The Baltimore sub-station is, at present, equipped for 40,000 Kva., and space is provided for additional transforming and switching apparatus. The present equipment consists of four 10,000 Kva. three-phase transformers, which, because they are the largest transformers ever built, are of particular interest, They are of the water-cooled type, and are used to step down the 25-cycle current from 70,000 volts to 13,200 volts for distribution. The appearance of one of these transformers is shown in the illustrations but these do not give an adequate idea of their size. The tank is elliptical, having an overall length of In feet 11 inches, and an overall width of 8 feet 8 inches. The height to the lop of the terminal is over 16 feet, and the joint between case and cover is 11 1/2 feet from the door. The total weight of each transformer, complete, with oil, is about 145,000 pounds, or nearly 75 tons. The transformers are of the core type, water-cooled. The cooling water is visible at its exit, so that any stoppage or inequality of flow in the parallel cooling coils can be detected easily. The tanks are of boiler iron, with welded seams and crowned cover and bottom. The Westinghouse condenser type of terminal bushing is used, as the specifications called for bushings to withstand a test of 180,000 volts each for one minute. These bushings are made up of alternate layers of insulating and conducting material which, In producing a uniform distribution of dielectric stress in the insulation, enable the use of a much smaller bushing. The method used in installing these large transform ers is also of interest. On account of railroad clearances and the great weight of each unit, the core and coils, the tank, cover, base and details, and the oil were received from the factory separately. At the Baltimore sub-station a railroad siding runs directly into the station. Paralleling the siding in the station are the transformer compartments, built of concrete. On receipt of the transformers in the sub-station it was necessary to assemble them, one at a time, on a truck running on a track having the shine center line as the siding, but wider gage. The corner of this truck is shown in one of the photographs, Lifting and moving was done with an electric hoist. After each transformer was assembled, the truck was pushed along its track to the proper compartment, and the transformer rolled in on its own wheels, the floor of the compartments being at the level of rails on the truck. The oil, received in tank cars, was pumped into the tanks after the transformers had been thoroughly dried out.

Underneath each transformer is a pit connected with a 10-inch main for draining the tanks in case of emergency. I he top of each transformer is connected through a hack pressure valve to an 8-inch main to relieve any possible rise of pressure in a tank. The arrangement is such that oil blown out of one transformer cannot enter another The cooling system is arranged to preclude a shut own from lack of cooling water. Normally, w_____r is obtained from a well near the sub-station. Connection is also made to the city mains for use in ease of deficiency of the well, and the large storage tank on a steel tower, shown in the view of the sub-station, is built for the use in ease of failure of both sources. In connection with this emergency system, there is a spray cooling system which makes it possible to reuse the cooling water, the storage tanks supplying only the deficiency caused by leakage and evaporation. Normally the heated water is discharged into a nearby stream. The transformers were furnished In the Westinghouse Electric and Manufacturing Company, and were built at their last Pittsburg (Pa.) works.

In the Federal Court at St. Louis Judge Adams fixed the valuation of the Municipal Water Company’s plant at Port Smith, Ark., at $500,000. The company’s franchise stipulated that at the expiration of the franchise the city was to have the privilege of purchasing the system, and suit was instituted to determine its value. The franchise expired nine years ago.

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