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First Electric - Driven Freighter New Trail Is Blazed by Applying Magnetic Pro- pulsion to Slow Speed Commerce Carrier HE steamer Ectirpsr, first elec- ; trically driven general cargo merchant vessel in the United States, will be placed in service in Jersey City, N. J., in October. She also is the first electrically propelled yessel owned by the United States shipping board and is under charter to the American line of the International Mercantile Marine Co. The Ecuipse is of 11,868 tons dead- weight, 440 feet length and 56 feet beam. The boat was built by the Union Iron Works, San _ Francisco. The electric propulsion machinery was manufactured by the General Piectie Co., Schenectady, N.. Y.; and installed by the Vulcan Iron Works, Jersey City. Propulsion machinery consists of a marine turbine generator set and a 3- phase induction motor, which drives the single propeller shaft at 100 revo- lutions per minute. There also are two steam-engine driven, 125-volt al- ternating current exciters and a con- trol equipment for maneuvering the ship. Turbine Automatically Governed The turbine is of the horizontal Curtis type operating normally at 3000 revolutions per minute and was developed by the General Electric Co. for marine purposes. The gov= ering system is so arranged that the turbine' is controlled by a hydraulic variable speed governor at speeds from 20 to 110 per cent of normal. It is further provided with protective devices in the way of a centrifugal type pre-émergency. governor con- trolling the speed up to 115 per cent of normal and a ring type emergency governor, which prevents the turbine from running at speeds exceeding 125 per cent of nonmal, : The 3-phase generator of 2300 volts is especially designed for marine serv- ice. It incorporates several features necessary to meet the particular re- quirements of the class of work it is called upon to do. The stator con- sists of a cast iron, l-piece frame with openings in the top for ventila- tion. The core is built up of an- nealed segments of thin sheet iron of special material to insure low core loss and is held in place by heavy cast iron frame flanges at -each end. Windings are formed coils pressed from enameled cable, each turn con- sisting of rectangular copper strips in multiple. Eddy . currents. are eliminated by the strips being well insulated from each other. Ventilation is provided by a centrifugal fan mounted at each end of the rotor. The propelling motor is an induc- tion motor rated at 3000 horsepower and revolves at a normal speed of 100 revolutions per minute, which gives a total reduction from turbine speed to propellor speed of 30 to. 1. The motor is ventilated by a motor driven blower. Construction of the motor stator is similar to the gen- erator stator. The rotor consists of a cast iron spider keyed to the shaft on which the rotor core is assembled. The windings consist of insulated copper bars. Control Equipment Centralized Control control group, equipment consists of a a water-cooled _ re- sistor, and a control panel. The water-cooied resistor is inserted in the motor circuit, when operating the motor at low speeds, and is mounted on top of the control panel. The panel is a structural iron cell faced on one side by a sheet steel plate upon which are mounted all the elec- trical instruments and the electric and speed levers for normal operation of the machinery, the two levers being mechanically interlocked, to prevent improper starting and running condi- tions. The electric lever moves the master controller, which in turn energizes the contactors of the con- trol group, normally operated by solenoids, In addition to the speed and elec- tric levers, there is a field resistor for regulating the generator field re- sistance and an auxiliary handle for SACIT Ee" we.7/ "a EXCITER Wo 2 12S TURBINE GENERATOR LEADS QDIS-1/OF COVIFOL GROUP CEOS-/28-A PANEL OS GIA, PESISTOR AC. GENEPATOR FIELD LEADS, « ywe CONDUCT OP SPLED /NOICATORP LLADS . A.C. AIOT OR IAIN LEAOS AC.MoroR SECONDARY L£LADS TWwe LEADS IN PARALLEL PER? PHASE WSTA WATER COOLED J INTAKE FOR SEA WATER HT I ECLIPSE LAYOUT OF ELECTRIC PROPULSION SYSTEM ON FREIGHT STEAMER 583 li i