Electric Railway Engineering

UNIVERSITY OF ILLINOIS LIBRARY Volume Class Book i^LL fTir^fa '"-^alljf' Return this book on or before the Latest Date stamped below. A charge is made on all overdue ^°°^^S- U. of I. Library ^tMK xb iS'- ^^^, i€ i^l; .^!^ 1762S-S ELECTRK^ RAILA\ AY ENGINEERING ELECTEIC KAILWAY ENGINEERING BY C. FRANCIS HARDING, E. E. professor, electrical engineering; director, electrical laboratories, purdue universitt; associate American institute electrical engineers; associate AMERICAN electric RAILWAY ASSOCIATION ; MEMBER SOCIETY FOR promotion OF ENGINEERING EDUCATION McGRAW-HILL BOOK COMPANY 239 WEST 39TH STREET. NEW YORK 6 BOUVERIE STREET, LONDON, E. C. 1911 Copyright, 1911 BY McGraw-Hill Book Company Prhited and Eleclrolyped by The Maple Press York. Fa. PREFACE. To students in technical universities who wish to specialize in the subject of electrical railway engineering and to those who understand the fundamental principles of electrical engineering and are interested in their application to electric railway practice it is hoped that this book may be of value. While it is planned primarily for a senior elective course in a technical university, it does not involve higher mathematics and should therefore be easily understood by the undergraduate reader. The volume does not purport to present any great amount of new material nor principles, but it does gather in convenient form present day theory and practice in all important branches of electric railway engineering. No apology is deemed necessary for the frequent quotations from technical papers and publications in engineering periodicals, for it is only from the authorities and specialists in particular phases of the profession that the most valuable information can be obtained, and it is believed that a thorough and unprejudiced summary of the best that has been written upon the various aspects of the subject will be most welcome when thus combined into a single volume. The author wishes to express his appreciation of the assistance of Mr. Emrick, instructor in electrical engineering at Purdue University, in preparing illustrations for the book and to those students who by thesis investigations have added to its value. LaFayette, Ind., September, 191 1. ^01359 . TABLE OF CONTENTS. PART I. Principles of Train Operation. I. History of Electric Traction 3 II. Traffic Studies (predetermined) 13 III. Traffic Studies (existing) 24 IV. Train Schedules 30 V. Motor Characteristics 35 VL Speed Time Curves (components) 48 VII. Speed Time Curves (theory) 59 VIII. Distance, Current and Power Time Curves (theory) 66 IX. Speed, Distance, Current, and Power Curves (concrete examples) 71 X. Speed Time Curves- (straight line) 78 PART II. Power Generation and Distribution. I. Sub-station and Power Station Load Curves 87 II. Distribution System 91 III. Substation Location and Design 104 IV. Transmission System 131 V. Power House Location and Design 145 VI. Bonds and Bonding 170 VII. Electrolysis 178 VTII. Signal and Dis])atching Systems 188 PART III. Equipment. I. Track. Layout and Construction 205 II. Rolling Stock 219 III. Motors 232 IV. Types of Control 246 V. Brakes 259 VI. Car House Design 277 VII. Electric Locomotives 288 vii Viii TABLE OF CONTENTS. PART IV. Types of Systems. 1. Alternating Current vs. Direct Current Traction 305 II. Electric Traction on Trunk Lines 319 PART 1. PRINCIPLES OF TRAIN OPERATION. CHAPTER I. History of Electric Tr.\ction. Although it is not the purpose of this treatise to relate facts, but rather to study the engineering and economic problems encountered in electric traction, yet it seems advisable to re\dew briefly the history of the development of the electric railway by way of introduction. Two distinct epochs were encountered in the brief period in which electric traction has come to the front. The first was that in which the experimental designs were hardly more than models operated with primary batteries. Occasionally during this period, however, enthusiasts who did not realize the insuperable financial drawbacks of primary battery operation constructed and experimented with cars of considerable size operated in that manner. Such was the car constructed by Page in 1851 for the Washington and Baltimore Railroad, which made use of a 16 h. p. motor supplied with power from two large Grove cells made up of platinum plates 11 in. square. This first epoch was soon brought to a close, however, partly by the foresight of the inves- tigators who realized the limitations of the primary battery and partly by the failure of all attempts to commercialize the primary battery car by those who had continued to experiment therewith. The second epoch opened, after a brief interval of inactivity, simultaneously with the development of the reversible dynamo. In the development of this machine progressive experimenters could foresee the beginnings of electric traction upon a practical basis. Bearing in mind the existence of these two periods, the history of electric traction will be considered, greatly abstracted, but as nearly as possible in chronological order. Since electric traction has ever been dependent u})on the electric motor and the latter upon the discovery by Faraday, in 1821, that electricity could be made to produce mechanical motion, the latter date rather indirectly and vaguely marks the birth of 3 4 ELECTRIC RAILWAY ENGINEERING. the subject under consideration. America has the honor of first applying the electric motor to a car, model though it was, while later developments vibrated from America to Europe and back to America with a rapidity difficult to follow with accuracy. A poor blacksmith of Brandon, Vt., by the name of Thomas Davenport has the honor of first making this application of electric motor to a car in 1835, the motor having been constructed by him several years previous. During the short period of six years it is said that Davenport constructed over a hundred electric motors of various designs. That which was described as having been exhibited by him upon a car at Springfield and Boston, Mass., consisted of a revohing commutated magnet which was caused to attract sta- tionary armatures arranged around the periphery of its path of revolution. The car thus equipped was operated upon a small circular track. About the year 1838 Robert Davidson of Aberdeen, Scotland, built a much larger motor placed upon a battery car 16 ft. by 5 ft. in dimensions of the gauge then standard and operated same with 40 cells of battery consisting of iron and amalgamated zinc plates immersed in dilute sulphuric acid. It is of interest to note that after several successful trips over Scotland railways this car was purposely wrecked by steam railway engineers who were afraid it would supersede types in use at that time. Two rather fundamental patents were issued in England about this time, one in 1840 to Henry Pinkus involving the use of the rails for current conductors and another in 1855 to Swear which, although applied to telegraphic communication with moving trains, comprised the basis of the present current collect- ing trolley. Patents were also granted in 1855 by both France and Austria to Major Alexander Bessolo which covered the same fundamental principles but which described more in detail the third rail conductor, the insulated trolley, and even suggested central station supply. The experimental work in this country of Prof. Moses G. Farmer in 1847 ^^'^ Thomas Hall in 1850 might be considered in particular because of the use for the first time of the rail as a conductor and the adoption of a geared speed reduction between motors and dri\ing axle. The work of Page, previously men- HISTORY OF KLECTRIC TRACTION. 5 tioned, deserves prominent mention at this time. For many years after these experiments investigations in electric traction seemed to be dormant, largely due to the general realization of the impracticability of the battery as a source of energy. The second era of electrical railway development opened about the year 1861 when Pacinotti invented the reversible continuous current dynamo. From this invention may be said to have arisen all modern generators and motors. While these were gradually developed by Gramme and Siemens, Wheatstone and Varley. Farmer and Rowland, Hefner-Alteneck and others, Wheatstone and Siemens having almost simultaneously developed self- exciting generators equipped with shunt and series winding, respectively, yet a considerable period of time elapsed before these developments were effectively applied to traction. The work of George F. Green, a poor mechanic of Kalamazoo, Mich., has been quoted as the connecting link between the two eras. Although he began his experiments as late at 1875, after the development of the dynamo, his first model road reverted to the battery delivering current to the car over the operating rails. Although Green proposed the trolley for his experimental track, he did not make use of it. The following work of this man is rather pathetic, in that he constructed a car about the year 1878 large enough for two people and realized the advantages of the dynamo for supplying energy for same. He did not understand how to construct this machine himself, however, and was not financially able to procure one of the few being constructed abroad at that time. He applied, in 1879, for patents which would probably have been of considerable value at that time, but because of limited funds and the fact that he was obliged to act as his own patent attorney, his claim was rejected and only fmally granted in the year 1891 after a belated appeal to the cir- cuit court of the District of Columbia. The first electric road operating on a practical scale was the one exhibited by Siemens and Halske at the Berlin Exposition in 1879. This consisted of an oval track about 1/3 mile in length upon which an electric locomoti\e was operated with three small trailers accommodating from 18 to 20 passengers.

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