The Montgomery advertiser., 1901-09-12
ELECTRICAL ENGINEERING
By Arthur E. Watson, A. M. ARTICLE TX.
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service involve generators, means or us devices. Direct currents are commonly employed and the system operated on the Constant potential principle. one to the feeder and trolley wires the oth- ec to the ground" this latter consists of the combination or rails electrically connected together and to bare wire laid under the pavement also connected to return feeders strung on poles or laid tn under ground conduits Sometimes both wires are insulated and suspended tems; in other cases third raiI IS employed for the supply return being made by the other two. Nearly all that was explained In artl- cle regarding generators for incandes- cent lighting is equally applicable to railway generators. The distinguishing a potential of 800 to 66o volts instead of 125 volts. and for extreme mechanical strength. Principles of distribution. of the current will be included in article Il. In this paper especial attention is CTS.
 Not to overlook pioneer electric rail- ways there may be mentioned the one constructed by Sicmens in Berlin in lS1S; Edison in Menlo Park in 1880; Van De- goele in Chicago. and Montgomery, Ala; all in the early sos .n some cases the wheels were insulated from axles and rails insulated from ground. Short used
 
 conduit and brought supply from an arc light dynamo and used rails for return. Daft at one time, employed double over occasionally this would jump the wires and smash through the top of tho car. Van .Depoele is accredited with the in yenon of the spS tbs smpe his patent by the Thomson-Houston Com pany contributed not little to their sue cess in developing electric ;ts .h traction Ed,snn Company. and equipped the first success full road in Richmond in 1887. In 1889 two important routes in Boston were electri- cally operated. The Westinghouse Com pany made it's first motors in lS9).
 Ordinary railroad motors have one bearing on the axles and other end rests n ore expensive method suspends the mo. tor in its center of gravity in sort of cradle: although the bearing on the shaft transmitted. The wheels consequently do not hammer the rails so violently and the destructive jar is largely removed from the motor windings. Connection between armature shaft and axle Is made by gears. Some locomotives have been made in which the armature shafts were hollow and slipped directly on the axle; 9 clearance of an inch or more Is allowed and the motor is thereby fexibly suspended. Such motors are very heavy ana inaccessible for repairs. Gearing, | though noisy, is reliable, allows the ar mature to rotate at reasonable high speed, and permits ready removal On the basis of the old style horse car, motor would be sufficient for ordinary traction. Spragues original motors for the Richmond road were of fhe single between armature and axle. The weight of motors, together with that of the stronger truck, proved too great load nd eetrG and heavier trucks. md cars were needed, with a demand for quick starting-even with heavy loads on steep grades stronger motors were continually in uo- nIand. Successive stages were for each of the two motors, 5. 7.5 10, 15 and now 25 II. P. for surface roads and 50 H. P. The stanGard motor made hv t',. Tbomson-Houston Company between 1888 and 1894. It has bipolar field of wrought iron forgings, smooth core sur face-wound armature. on same princi. pie as illustrated in figures 8 and of article 1; double reduction gears, though oinion is close besides the intermediate gear, but the axle gear Is omitted; ,en- tire structure unprotected from water eight revolutions to axle's once; weight about zoo pounds; rating 10 H. F. Oth- CT sizes of the same type were made for 3. 10 and 20 H; P Originally manufac. of cast iron and heavier weight, the Westinghouse Company. soon brought out the four-pole type. Only a single set of protected from dirt: besides being lit- tie lighter than the earlier form it's ar mature speed was only one;third as duced another type. Bipolar inclosed fields of wrought iron. smooth core ring q, mature and single reduction gears characteristics. A sheet iron pan sur rounded the motor and served to keep out water when the car was running through puddles. A succeeding type was more completely waterproof and conse- uuently denoted as w. P. It follows the Westinghouse style of hinging the upper field magnet, but otherwise is unique in having but a single field spool--as wis ible on the upper pole piecs lower half of field is shaped like a tub. with suita- ply shaped pole piece in the center ar mature is toothed ring about IS inches in diameter and inches long axially, wound with copper ribbon: gears inclosed and having the same speed reductions as the s. k. as the e. E. sOO (Scn pounds draw-bar pulp. there are four poles. but only two field coils; and armature is a toothed weight is only 1,60O pounds. Latest types by both General Electric and .vesline- commc nj. e., four laminated poles with winding on each: cast steel body or frame: tC othed drum armatures with two and sometimes three coils in each slot
 
 for different maximum speeds h.' "arring the number of conductors on the arIna- ture, thus the w. P. 50 motor (25 H. F ] was made with 5, : or turns of wire per e mmutator segment. and the speed were in the inverse ratio; with only , turns the copper could be of about twinc the cross seotCn of that used for tCrns, to generate the requisite counter cleo tr"mC tive force the former would need to revolve about twice as fast as the lat ter, thereby doing twice the work, and requiring twice as much current.
 Power or activity being the product If torque and speed, there are few occa- sions when the motor develops its full rating. At start, the cure mt and torque are large. buL the speed is small hence a level track the tOrque is small and the produce again small; between the two limits, as in climbing a grade, the tul! power may be realized. Indeed, the cOm- mon rating is somewhat fictitious, for factory tests have demonstrated that fl tie will be left of the motor but ashes and slae. 25 H. P. railroad motor sdapted to continuous work, such as driving d shaft in q mill. Is rerated at 10 H. p.
 One of the most serious and interesting factors of electric railway motors Is the method of controlling their speed To in- sert a rheOstat in the ctrcut Is d natural re course, but this represents considerable waste of energy. The case is analogous | by throttling the supply. Spragues | sought to mitigate the waste by letting | the field magnets of the motors serve as | rheostats Each field of the two motors on each car was wound in three sections; ! these twelve coils were then coupled in l tiple, whereby the electrical resistance of circuit and strength of magnets were