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© 7S PRESIDENT. HOOVER head is of cast steel construction and the upper halves of both the high and low pressure Cas- ings are hinged to facilitate inspection. Control of the steam flow is by means of the main throttle valve, and three subsidiary hand valves which permit minor steam flow adjust- ment without the necessity for throttling the pressure. The main throttle valve is remotely controlled from the main operating panel by means of a lever which actuates a hydraulic, oil operated mechanism. The hydraulic mech- anism is inter-connected with the lubrication system and an over speed tripping device which cuts off the steam supply automatically in case of overspeed or cessation of oil supply. The turbine may be controlled either for con- stant speed or for constant steam flow as de- sired. In the latter case the speed governor is set to function at a few revolutions above that obtained through the steam flow setting as reg- Main Switchboard in Engine Room ulated by the hand valves. In this manner it is possible to operate at full power even in rough weather, without danger of the propeller racing in case it should emerge from the water. The turbine operates in but one direction of rotation and has but two steam sealing glands, one at each end of the turbine. There are two extraction openings for bleeding steam for feed water heating. The high pressure opening pro- vides steam at 65 pounds gage pressure thus permitting of the attainment of 300 degrees Fahr. feed water temperature. The low pres- sure opening provides steam for the low pres- sure feed water heater at slightly above atmos- pheric pressure. As the turbine generators are electrically disconnected during warming up, this process is greatly simplified. They may be allowed to idle at slow speeds under their own steam with the certainty that there is proper heat distribu- tion. A hand turning device is provided for use when taking clearances, examining shaft bear- ings, etc., but it is not otherwise used. The main generators which are directly con- nected to the turbine shafts are of the totally enclosed, internally ventilated type, and are provided with external air coolers. Complete assurance against deposits of oil or dust on the windings is thus assured and therefore, long life of the insulation. The fan which cir- culates the air through the windings and thence through the air cooler is situated on the end of the rotor shaft. The tubes in the air cooler are supplied by circulating water from the main circulating pump discharge. The generator is of the two pole type. The rotor is a solid steel forging and has slots milled in its face in which the field windings are imbedded. The stator frame is of built up steel plate construction. The core is made up of laminated plates in which slots are provded for the reception of the windings. Electric heating coils are located inside of the inner shields for the prevention of moisture and accumulation on the windings during pe- riods when the generator is idle. The tempera- ture is kept at'just slightly above room tem- peratures (2 to 4 degrees Fahr.) in order to prevent condensation. The main propelling motors are of the highly efficient synchronous-induction type _ operat- ing at unity power factor. The stator frames are of built up steel plate construction, and the rotor spiders of cast steel. Like the genera- tors they are supplied with stator temperature detectors and heating coils for the prevention of condensation on the windings during idle periods. The control panel has mounted on its face the various levers for maneuvering the ship, the rheostat control wheels for adjustment of the generator and motor fields and the instru- ments for measurement of power. In the upper center of the panel are situated the steam and vacuum gages and the clock. Cross tie busses with switches are provided which permit of the parallel operation of the scasmssihiipinissiniahomansieidieiaitesinzaiaiaiadb ten iceccied nampsaiie see oe et Electric Propulsion Equipment S.S. President Hoover Two Main Turbine Generator Sets—Turbine rating; 10,100 k.w., 2660 r.p.m., 16 stages. Generator rating; 10,100 k.w., 2660 r.p.m., 4800 volts, 3-phase. Steam conditions at throttle valve; 275 lbs. gage, 200 degrees Fahr. superheat. Vacuum, 28.5 inches in turbine exhaust casing. Two Main Propulsion Motors—Synchronous induction type; rated maxi- mum continuous, 10,100 k.w., 133 r.p.m., 4800 volts, 3-phase. Two Propulsion Motor Ventilating Fans——Motor rating; C.D.M.—125, 22/40 h.p., 600/740 r.p.m., 230 volts. Two Surface Air Coolers for Generators—One surface air cooler for each main generator, consists of two sections, each rated 2600 sq. ft. of cooling surface, 2-pass, 150 tubes. One Control Panel with Two Control Groups—Each group consisting of igh voltage and low voltage contactors. The panel contains necessary electrical instruments, field-rheostat adjusting handwheels, electric speed indicators for motors and turbines, and the main operating levers. ny 32 € MARINE REvVieEw—August, 1931