. Electric trains . e , ofwhich an illustration is given in Fig. 88. For the commonly-acceptedbasis of rating of railway motors, namely 75° C. thermometrically-determined rise of temperature after one hours run at constant load,the continuous motor has a capacity of 240 hp, as against a capacityof only 115 hp for the single-phase motor. The two motors havesubstantially the same over-all dimensions and weight, and yet thesingle-phase motor has only half the capacity of the continuous-electricity motor. It is not alone that single-phase motors are much larger andheavier for a given rated o
. Electric trains . e , ofwhich an illustration is given in Fig. 88. For the commonly-acceptedbasis of rating of railway motors, namely 75° C. thermometrically-determined rise of temperature after one hours run at constant load,the continuous motor has a capacity of 240 hp, as against a capacityof only 115 hp for the single-phase motor. The two motors havesubstantially the same over-all dimensions and weight, and yet thesingle-phase motor has only half the capacity of the continuous-electricity motor. It is not alone that single-phase motors are much larger andheavier for a given rated output, but also the remainder of theelectrical equipment required on the single-phase system is verymuch more bulky and heavy than the corresponding apparatus forcontinuous equipments. As to the single-phase motor, efforts have been made to reduce its SUMMARY AND CONCLUSIONS 189 size by employing a blast of air provided by a ventilating set locatedat some suitable point on the truck, and from which air is forced to. Fig. 88.— Single-phase Rating .... 115 (including Gearing) . 2*75 at One-hour Rating . 600 rpm. and through the motor. By these means, which are employed on theSiemens and the Westinghouse equipments on the single-phase trains I90 ELECTRIC TRAINS for the Heysham section of the Midland Railway, the motor weighthas been brought down to 176 kg per hp as against 24 kg per hp forthe weight of the single-phase motors on the line. On motors, the only artificial ventilation is that provided by thesmall amount of air drawn through a hole in the armature shaft andsubsequently escaping from the motor through openings in the Dawson, who has designed the electric trains on the Rail-way, considers this to be the best plan, notwithstanding the somewhatj^jreater weight of motor. On p. 165 of his book, entitled ElectricTraction on Railways, Mr. Dawson states— Such methods (alluding to ventilation by me
Size: 1313px × 1902px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1910
