. Electric traction and transmission engineering . kcoS ^ >< / / oive 5 con: UMP ION / / RUN Fig. 53- 20-second stops but no coasting, is shown in Fig. 53. Thiscurve is based on data obtained from Fig. 31, on which anumber of braking curves may be drawn corresponding toruns of various lengths. Proportionately less of the energy taken from the supplycircuit is used to overcome the losses in other than trainresistance for long runs than in short runs, and thereforethe power consumption per mile is decreased by increasingthe lengths of runs. This is also shown i
. Electric traction and transmission engineering . kcoS ^ >< / / oive 5 con: UMP ION / / RUN Fig. 53- 20-second stops but no coasting, is shown in Fig. 53. Thiscurve is based on data obtained from Fig. 31, on which anumber of braking curves may be drawn corresponding toruns of various lengths. Proportionately less of the energy taken from the supplycircuit is used to overcome the losses in other than trainresistance for long runs than in short runs, and thereforethe power consumption per mile is decreased by increasingthe lengths of runs. This is also shown in Fig. 53 for theparticular car under consideration; the curve of power con-sumption per car mile without coasting was computed in 12850 40 H30 z Ul 10 TRACTION AND TRANSMISSION. ^ -^ 6-CARTRAlN,-4 MOTOR .<^^ ^—^TONS. AVQ. BRAKING .Jy ^<CS^^MILES PER HR. PER SEC. STAT10N-<,V y/ <<^ /fiz 1 1 1 ul RATE OF ACCELERATION IN MILES PER HOUR PER SECOND. Fig. 54-. RATE OF BRAKING IN MILES PER HOUR PER SECONDFig. 55: connection with Fig. 49. The effect on schedule speed andon energy consumption of changes in the rates of accelera-tion and braking is not as conspicuous on long runs ason short ones. ENERGY CONSUMPTION. 129 The schedule speed of railway cars depends to a greatextent upon the duration of the stops for the purpose oftaking on or discharging passengers or freight. Obviously,the longer the period of standstill the lower will be themaximum schedule speed attainable by a given equipment. An increase in the time of coasting results in a reductionof the power consumption. The results of a series of testson a 6-car train of the elevated railway in New York City 50 40 1-30 z o DC 120 10 6-CAR TRAlN,-4 MOTOR CARS,-154 TONS. \VQ. BRAKING MILES PER HR. PER SEC STATION STOP-14SECONDS. PERC ^^77-52 ^srTTvS- PERC ENT SA VING iN~-p7^ N \ 2 3 4 5 6 TIME IN SERIES POSITION,SECONDS. Fig. 56. made by H. S.
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