. Electric railways, theoretically and practically treated . 10 20 30 40 50 60 70 SO 90 100 110 120 130 140 150 160 AMPERES Fig. 9. —MOTOR ACCELERATION CURVE. A F a = za X Let W = the weiirht in tons = w 2000 F F W X X 2000 W .01098 FW It is obvious from the preceding equations that 91. i effort will accelerate one ton at the rate of i 31. perH. per 5. It is also evident that the rate of acceleration 20 ELECTRIC RAILWAYS. varies directly as the force applied and inversely as theweight of the body undergoing acceleration. Motor Acceleration. — A cur
. Electric railways, theoretically and practically treated . 10 20 30 40 50 60 70 SO 90 100 110 120 130 140 150 160 AMPERES Fig. 9. —MOTOR ACCELERATION CURVE. A F a = za X Let W = the weiirht in tons = w 2000 F F W X X 2000 W .01098 FW It is obvious from the preceding equations that 91. i effort will accelerate one ton at the rate of i 31. perH. per 5. It is also evident that the rate of acceleration 20 ELECTRIC RAILWAYS. varies directly as the force applied and inversely as theweight of the body undergoing acceleration. Motor Acceleration. — A curve, termed motor accelera-tion curve, Fig. 9, may be plotted for a particular motor. 0 20 40 60 80 100 120 140 160 180 200 AMPERES-Fig. 10.— MOTOR CURVES FROM WHICH FIG. g IS CALCULATED. equipment as follows. The complete weight of the trainin tons, including trucks, motors, brake equipment, andthe number of motors to the car, is determined. From ANALYSIS OF TRAIN PERFORMANCE. 21 this data is obtained the gross tons per motor. The accel-eration vahies corresponding to the tractive effort per tonper motor is determined at the various current imputs anda curve of acceleration and current plotted. As an example,assume a car weighing 32 tons including passengers,equipped with four type 81 Westinghouse motors. Eachmotor will accelerate 8 tons. Referring to the tractive ef-fort curve for this particular motor, Fig. 10, it is obviousthat with a current input of 100 amperes, the motor willexert a tractive effort of 1,260 lbs. or lbs. per ton,which is equivalent, from acceleration equation, to an ac-celeration of M. per H. per S. In a similar mannervalues are obta
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