CO129-415 - Governor Sir May - 1914 [12] — Page 458

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OIL ENGINE.

11. To be an oil engine of the high speed vertical type, develop- ing 20 horsepower at approximately 800 r.p.m. when running on To be petroleum of a recognised quality for oil-engine fuel. furnished with all necessary water tanks and piping, exhaust silencer, fuel tank and piping, and the usual spares and accessories.

The general design of the engine to be as described hereunder :-

The cylinders to be of close-grained hard cast iron, both the cylinders and cylinder heads to be water cooled. The piston and connecting rod to be capable of being withdrawn by removing a cylinder head and without removing the cylinder from the crank case.

The pistons to be of special cast iron, with cast iron piston rings, accurately ground and fitted.

The connecting rods to be steel forgings and the crank shaft to be of steel, machined from the solid.

The governor to be of the spring-loaded centrifugal pattern, driven off the cam-shaft.

Magneto-electric ignition to be fitted.

Cooling water circulation to be maintained by a gear-driven

pump.

Tanks of extra capacity for tropical climate to be provided.

The bedplate of the engine to be extended to carry the continuous current generator described in Clause 12.

GENERATOR.

12. To be a shunt-wound continuous current dynamo giving an output of 10 KW. at 110-160 volts when driven at 800 r.p.m. The machine to have a pressure regulation of 110 to 160 volts to enable it to be used for charging an accumulator battery of 60 cells and to be designed to be driven direct-coupled to the oil engine specified above, the dynamo also to be capable of running the motor-alternator when the battery is not in use. To be of the protected type with bracket

bearings.

The insulation between conductors and frame to be capable of withstanding an alternating pressure of 1,000 volts for a period of 5 minutes immediately after a 6 hours' run at full load.

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At the end of a 6 hours' run at full load at full voltage the temperature is not to rise more than 33° C. above the temperature of the surrounding atmosphere.

The generator to be provided with a field regulating rheostat giving the range of voltage required. Temperature rise of rheostat not to exceed 100° C.

MOTOR GENERATOR.

13. To consist of a direct current motor running direct coupled to a single phase alternator which carries the insulated dise discharger on a shaft extension. These machines to be mounted on the same bedplate. The motor to take its current either from the accumulator battery or from the charging dynamo, and to drive the alternator at approximately 2,250 r.p.m. The alternator at this speed to be capable of delivering 5 KVA. at 500 volts, 300 cycles.

A starting switch with no-voltage and over-load release for the motor, and a field regulating resistance for each of the machines to be provided.

The machines and rheostats to comply as to pressure tests and temperature rise with the Specification for the Generator, Clause 12.

Suitable shunt resistances to be furnished and connected across the windings of the two machines to guard against damages by high frequency surges induced by the high frequency circuits during transmission. A sufficient quantity of spare parts to be furnished.

SWITCHBOARD.

14. To consist of enamelled slate panels mounted in suitable angle-iron framing, set at a convenient distance from the wall of the engine room, and furnished with all necessary measuring instru ments, switches and cutouts for controlling the various circuits, together with all back connections, thimbles and usual accessories. The switchboard to be connected to the various machines and the battery by high tension vulcanised indiarubber lead-sheathed cable of ample capacity for carrying continuously the maximum currents in the respective circuits.

ACCUMULATOR BATTERY.

15. The battery to consist of 60 cells in glass boxes with a capacity of 270 ampere hours at the 3-hour rate of discharge. The maximum rate of charge to be 70 amperes and the maximum rate of discharge to be 90 amperes. To be complete with all fittings, terminals, insulators, spray plates, stands and acid.

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