. The Street railway journal . alternating current is used. It is sufficient forpresent purposes, therefore, to discuss the direct-currentand the alternating-current circuits separately, withoutany relation to each other. DIRECT-CURRENT CONTROL CIRCUITSDuring direct-current operation, switches 3, 2 or 1,4 according to direction of operation of one motor creasing the speed by weakening the magnetic fields. Themotors being of the compensated type permit of an enor-mous weakening of the fields at the commutators. Thefields are further weakened by the simultaneous closing ofswitches 9 and 19, and
. The Street railway journal . alternating current is used. It is sufficient forpresent purposes, therefore, to discuss the direct-currentand the alternating-current circuits separately, withoutany relation to each other. DIRECT-CURRENT CONTROL CIRCUITSDuring direct-current operation, switches 3, 2 or 1,4 according to direction of operation of one motor creasing the speed by weakening the magnetic fields. Themotors being of the compensated type permit of an enor-mous weakening of the fields at the commutators. Thefields are further weakened by the simultaneous closing ofswitches 9 and 19, and the speed becomes accelerated toconsiderably more than one-half of the normal runningvalue. The next movement of the controller handle opensswitches 8, 9, 18 and 19 (thereby increasing the strength ofthe fields); closes switch J; opens switch JR, and closesswitches G1 and M2, thus subjecting each motor unit inseries with four resistance sections to the full value of thesupply potential. It will be noted that the transfer from. FIG. 8.—LONGITUDINAL SECTIONS OF LOCOMOTIVE THROUGH CENTER AISLE, RIGHT AND LEFT VIEWS unit, and switches 12, 13 or 11, 14 according to direc-tion of operation of the other motor unit are keptclosed so that the main field circuits of each motor unitare connected at all times in series with the respec-tive armatures. At the moment of starting, switchesS, M and JR are closed, thus connecting the twocomplete motor units in series with each other and witheight sections of resistance. As the speed increases, switchesRi; R2, R3 and R4 of one motor unit, and switches RRrRR2, RR3 and RR4 of the other unit are closed in succes-sion, thereby increasing the voltage impressed on eachmotor unit until the two units are in series across the linewithout resistance. Switch 8 of one unit and switch 18 ofthe other are then closed simultaneously, thus placing aresistance in shunt to the field windings and thereby in- full series to multiple connection is accomplished witho
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
