The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

two propelling motors from either main gen- erator. Under this condition of operation, the turbine generator not in use, is shut down with its attendant condenser and auxiliary equip- ment. The equipment is arranged so that one main turbine generator furnishes power for driv- ing the port propulsion motor, and the second main turbine generator furnishes power for driving the starboard propulsion motor. Also, provision is made to allow either main turbine- generator to drive both the port and starboard propulsion motors at reduced speed (approxi- mating 104 revolutions per minute). The propulsion motors turn outboard when going ahead, the starboard propeller being right hand and the port propeller being left hand. Variation in propeller speed in either direc- tion is obtained by varying the turbine speed, and is directly under the control of the operator at the control panel. The direction of rota- tion of the propeller is reversed by changing the relationship of two of the three phases leading to the motors; this is accomplished by means of contactors operated by levers located at the control panel. The turbine generators always rotate in the same direction but, with both in operation, the speed of either propeller may be varied or reversed irrespective of the other. When one turbine generator is used for driving both propulsion motors, both motors operate at the same speed; this is true even though both motors are not rotating in the same di- rection. When starting, the turbine generators oper- ate at approximately one-quarter speed, and the propulsion motors are brought to approxi- mately one-quarter speed operating as induc- tion motors. The field windings of the gener- ators are temporarily over-excited to bring the motors fully into synchronism, after which nor- mal excitation is used. ° Two separate electric motor driven blowers furnish ventilation for the main propulsion mo- tors (one blower for each propulsion motor). The blowers for ventilating the main gener- ators are built into the generator rotors. A supply of direct current for excitation of the main generators and propulsion motors is provided by any one of the four 500-kilowatt, direct current geared turbine generator sets. Main Control Equipment HE main control panel with levers, hand- wheels, instruments, etec., is shown in an accompanying illustration. The reversing levers on front of the con- trol board reverse one phase when going astern. The governor levers adjust the speed of the main turbines to obtain desired propeller S. S. PRESIDENT “ROU Es speed which is one-twentieth of the turbine speed. In addition to the regular governor lev- ers there are two emergency speed control ley- ers, mechanically connected to the turbine gov- ernors in case of failure of the main levers. By means of the field levers excitation is ap- plied to the generators and motors, the first point of the lever applying excess excitation to the generator for pulling the motor in step as an induction motor, the second point apply- ing field to the synchronous motor with excess excitation remaining on the generator and the third point reducing the generator excitation to normal leaving excitation on the motor fields. All the above levers are completely inter- locked to avoid improper operation and to avoid operating the high voltage contactors with field on even though these contactors are capable of such operation. Two 500 K.W. Auxiliary Turbine Generating Sets On this control board are provided hand- wheels for controlling generator and motor field rheostats, switches for measuring on the temperature indicator the temperature of the generator and motor stators at three different points around periphery and switches and rhe- ostats for controlling the main motor ventila- tion fans. There is provided a complete outfit of in- struments by means of which the operator can visualize the behavior of the various machinery and know exactly how it is performing. By means of these instruments and meters the amount of power is indicated for any condition of running or maneuvering and the power is also recorded for any trip or part of a trip. The main boiler plant consists of twelve Babcock & Wilcox standard marine type water- tube boilers, arranged three abreast in two fire rooms with the drums athwartship. The boil- ers are built for a working pressure of 300 pounds per square inch and 200 degrees super- heat. The total water heating surface is about 57,600 square feet, and the total superheating surface about 5700 square feet. Each boiler MARINE REvirew—August, 1931 oo