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PLATE XII.-METROPOLITAN ELECTRIC SUPPLY COMPANY'S SARDINIA STREET STATION WITH PARSONS STEAM TURBINES COUPLED TO ALTERNATORS.

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THE NEW YORK PUBLIC LIBRARY

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PLATE XIII.-VICTORIAN RAILWAYS LIGHTING STATION EQUIPPED WITH FOUR 150-KILOWATT PARSONS TURBINE ALTERNATORS WITH EXCITERS.

and supplies single-phase current at 4000 volts and 50 periods per second, the speed of rotation being 1500 revolutions per minute. The results of tests on this machine are given in Chapter XI.

Plate XII. shows an installation of steam turbine alternators supplied by Messrs. C. A. Parsons and Co. to the Metropolitan Electric Supply Co. An injunction was obtained against this company to cease running at their Manchester Square Station unless the vibration (caused by reciprocating engines) was prevented. The company satisfied the plaintiffs by removing the reciprocating engines and replacing them by steam turbines.

In Plate XIII. is seen the interior of the Victorian Railways Lighting Station. Four Parsons turbo-alternators, each of 150 kilowatts capacity, and provided with exciters, are there installed and run in parallel. Ferranti rectifiers are used, and the current employed for both arc and incandescent lighting.

Turbine-driven alternators may be built either with fixed armature and rotating fields, or with rotating armature and fixed fields. For high voltages the former arrangement is considered the better, and is usually adopted.

Parsons turbines have been very successfully applied to the driving of rotary pumps. Plate XIV. shows a steam turbine driving a centrifugal pump. This was supplied by Messrs. C. A. Parsons and Co. to Messrs. Storey Bros. and Co., of Lancaster.

The pump is normally employed for supplying water at a pressure of 22 lbs. per square inch to an ejector condenser. The steam for the turbine is then reduced by a throttle-valve from 60 lbs. per square inch to 20 lbs. per square inch. The speed of the turbine is not controlled in the usual way, but by

the governor acting on another throttle-valve. The turbine and pump are also used as a reserve fire-engine in case the regular fire-engine kept by Messrs. Storey should fail. When thus used the steam is admitted to the turbine at the full pressure of 60 lbs., and the governor put out of action. The water is then delivered at a pressure of 80 lbs. per square inch. Air is prevented from entering the pump-shaft glands by subjecting these to water pressure. For this purpose a water-tank is arranged above each gland, in which a constant head of water (several inches) is maintained, any surplus water overflowing into another tank, from which it is drained away.

Multiple-action pumps can be driven by steam turbines to deliver water at very high pressure. Two sets of highpressure turbine pumps have lately been supplied by Messrs. C. A. Parsons and Co. to the Agent-General for New South Wales for use at the Sydney Waterworks. The first set comprises a steam turbine driving three high-speed centrifugal pumps. The three pumps working in parallel can raise 43 million gallons of water every twenty-four hours to a height of 240 feet, and working in series they are capable of raising 13 million gallons to a height of 720 feet. In the second set also one steam turbine drives three pumps. These in parallel can deliver 10 million gallons a day to a height of 80 feet, and in series 3 million gallons a day to a height of 240 feet. In both sets a surface-condenser for the turbine is provided with the circulating water passages arranged as a by-pass to the matu suction-ppe. Two air-pumps are provided, driven by worm gearing from the turbine spindle.

Pasens turbines are now largely employed to dive fans and airpropells and compressCTS The fans are usually of Gwing to the

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