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AUXILIARIES ON THE STEEL ELECTRICIAN—AT LEFT—CIRCUL ATING WATER PUMPS—AT RIGHT—ONE OF THE TWO WATT DIESEL ENGINE GENERATING SETS tion disconnects the generator from all active circuits and at the same time completes the series propulsion circuit for the remaining portion of the plant when set up for propulsion. The proper field circuit connections are also effected by the set-up switch in the various positions. An interlock is also provided to prevent connecting more than one generator to the auxil- iary bus simultaneously. The hand wheel at the top of the center panel of the dead-front propulsion group operates the engine room _ potentio- meter rheostat for emergency control of the propeller. The switch. handle at the bottom of the same panel connects the control to either the pilot house potentiometer rheostat, or to the one in the engine room. From the above, it is obvious that the control is arranged so that any combination of main generators may be used for propulsion. Also the voltage control system as_ installed, makes it possible to utilize the full engine capacity of any number of sets in operation. Thus, with two of the three generating sets in oper- ation, there is sufficient power to drive the vessel at 88 per cent speed, while one of the generating sets will furnish sufficient power to drive the vessel at 70 per cent speed. This makeS an exceedingly flexible pro- pulsion plant. The ability to use any one of the main generators for supplying power to the cargo handling machinery is another important point in the flexi- bility of the system. The STEEL ELEC- TRICIAN, therefore, carries only a small auxiliary oil engine generator set of 15-kilowatt capacity which is used chiefly when the vessel is laid up. The STEEL ELECTRICIAN is the first vessel to be fitted with an automatic power limit control. The function of this part of the equipment is to limit the power developed by the engines to a predetermined value in order to prevent detrimental over- load. The power limit control oper- ates in such a manner as not to in- 15-KILO- terfere in any way with the maneuy- ering of the vessel. The arrangement for connecting the three exciters to the busses consists of three hand wheel operated cam contractor switch groups, these groups being mounted back of the fourth panel of the main switchboard from the port side, and operated from hand wheels on the front. Each group pro- vides for connecting that particular bus to any one of the exciters. The system is such as to prevent parallel- ing the exciters. This provides com- plete flexibility of the auxiliary plant in a simple yet fool-proof arrange- ment. The engine room auxiliary feeder switches are made double-throw connecting to either of two of the auxiliary power busses, so that it is possible to divide the auxiliary load, when under way, between the three exciters. This makes it possible to utilize the full capacity of the three exciters when necessary, and also makes it possible to equalize the auxiliary load on the main engines. ENGINE ROOM OF THE STEEL ELECTRICIAN—AT LEFT LOOKING FORWARD, SHOWING ARRANGEMENT OF MAIN GENERATING SETS AND PROPELLING MOTOR—AT RIGHT—LOOKING TOWARD PORT SIDE, SHOWING ONE OF THE THREE MAIN DIESEL ENGINES CONNECTED TO 26 MARINE REVIEW—June, 1927 GENERATOR AND EXCITER