None
With very large telephone systems the multiple connections become so complicated that it is more advantageous to use two or more sepa- rate exchanges, interconnected by a number of "trunk lines." The number of the trunk lines must be sufficient to handle the trafSc during the busiest hours of the day. Dividing one exchange into several smaller exchanges has also the advantage that the subscribers' lines become shorter. When a connection is desifed between two subscribers connected to the same exchange, the operations are the same as with the above-described multiple switchboard. If the subscriber wanted is connected to another exchange, the operator merely receives the call and transmits it to a special operator in the other office, who completes the connection. Private-branch exchanges constitute a special case of the above scheme. The operator of the private branch completes the connection between subscribers connected to the branch. When, however, a connection is desired outside of the branch, she transmits the call to an operator of the main exchange, who in turn completes the connec- tion, or, if necessary, transmits it again to another exchange. The next development of telephone work is the long-distance trans- mission between cities. This trafSc is handled by special operators, so-called "toll" or long-distance operators, who make the necessary connections. General features of connections may be understood from the above description of small exchanges. Special details and the corresponding laboratory experiments are outside of the 458 TELEPHONY. [Chap. 20 scope of this work, which does not claim to give any but general information about telephone practice. Those speicially interested in telephony are referred to comprehensive treatises by Kempster B. Miller, A. V. Abbott, and others. 425. EXPERIMENT 20=H. — Influence of Resistance, Induc- tance and Capacity of the Line on Speech Transmission. — Con- nect up two telephones, to operate satisfactorily as regards talking and signaling; gradually increase the resistance of the line, until the words cannot be distinctly heard. Note a few values of resistance in the line, and mark the corresponding quality of speech as: excellent, good, fairly distinct, hardly intelligible, poor, etc. Repeat the same experiment with inductance in the line, instead of the resistance; also with a combination of resistance and inductance in series. If large condensers are available, they may be connected across the line, either in one place or in various places, in combination with the resistance in the line itself. This will show the effect of distributed and concentrated capacity, which sometimes impairs the quality of speech, particularly with long telephone cables. Having appreciably affected the transmission by means of capacity, connect up some induc- tance in series with the line so as to counter-balance the effect of capacity by producing electric resonance (§ 440). The use of induc- tance for counteracting the capacity effect in telephone lines has been proposed by Prof. Pupin; telephone lines provided with distributed inductance coils are now known as "loaded " lines. Appreciable disturbances in telephone lines are caused by light and power transmission Unes paralleling them. Magnetic fields, produced by heavy alternating currents, induce secondary currents in the tele- phone lines; this impairs the quality of the speech and sometimes makes talking practically impossible. String a power line in the laboratory, parallel with the telephone line, and observe the disturbances pro- duced. First use alternating currents and vary tbeir strength, fre- quency, the distance between the wires, and the mutual arrangement of the telephone and the power lines; observe in each case the effect on the transmission of speech. Investigate the effect of transposition of the telephone wires, and of the power wires, so as to compensate for the effect of induction. Try this in particular with a three-phase line. Then use direct current in the power line, suddenly vary its value, and observe clicks and sounds produced in the telephones. Finally use one wire as a common return (ground) for the telephone currents and the power currents; observe the effect produced on the quality of speech. Chap. 20] TELEPHONY. 459 The above combinations are those met with in practice, and are intended to illustrate the difficulties with which telephone engineers have to contend in the operation of their lines. Report the connections used in the experiment, the values of power current, the distance between the wires, with other factors, and the extent to which they were found to affect telephone transmission. State the effect of resistance, inductance, and capacity, and of their combinations. END OF veil. I. INDEX To Vols. I and II Air-brakes: automatic, ii, 287. motorman's valve, ii, 289. straight-air, ii, 284. triple valve, ii, 290. Air-gap: flux distribution in, i, 158. influence on magnetization curve. I. 145. Absolute electro -dynamometer, i, 84. Acceleration and retardation tests of cars. ii. 278; ii, 281. Acceleration limit on car controllers, ii, 271. Air-box test of alternators, ii, 130 Alternating-current plants, storage batteries in, i. 423. Alternating-current switchboards, ii. 238. Alternating-current wave form, ii, 210. Alternators and synchronous motors, i, 347. commercial tests, ii, 129. efficiency, ii, 129. in parallel. 492, i, 537. load characteristics, i, 349. maintaining constant voltage on . i, 364. no-load characteristics, i, 348. performance curves, i, 351. references to literature on, ii, 150. temperature rise, ii, 135. voltage drop, i, 349; i, 350; i, 351. voltage regulation, i, 349; ii, 138. Ammeters and voltmeters: calibration of A. C, i. 67. calibrating with milli-voltmeter and shunt, i, 65. calibrating with potentiometer, i, 82. commercial types, i, 35. construction and operation, i, 34. deflection on alternating current, i, 36. electro-dynamometer, i, 42. friction in pivots of, i, 42. hot-wire, i, 45. induction, i, 47. moving coil, i, 38. plunger type, i, 35. range of, ii, 237. recording, i, 63. requirements of good, I, 53. shunts, i, 40. Ammeters and voltmeters: soft iron core, i, 35. study of, i, 53. Thompson inclined-coil, I, 36. Ampere balance, i, 82. Ampere feet, ii, 49. Ampere-turns and flux density, I, 147. Amplitude of harmonics, ii, 224. Analysis of core-loss curves, i, 201. Analysis of wave forms, ii, 222. Analyzing tables, ii, 225. Apparent reluctance, ii, 146. Arc lamps: distribution of light about, i, 244. integrating photometers for, i, 246. operation of multiple, i, 234. photometry of, i, 243. regulating mechanism of multiple. 1. 232. regulating mechanism of series, i, 235. types of, i, 232. Armature reaction, effect on iroa loss, i, 321. Armature reaction, effect on magnetic leakage, i, 150. Armature windings: A. C. windings, ii. 188 bar-winding and coil-winding, il, 100- chain-winding, ii, 193. double-layer winding, ii, 195. experimental frame for. ii. 190. form of induced e.m.f. in. ii, 191. parallel connection of coils, ii- 196. series cooDection of coils, ii. 196. Direct-current windings, ii. 197. barrel winding, ii, 200. double-layer bipolar, ii. 199. evolute winding, ii, 200. fractional -pitch, ii. 205. multiple, ii. 204. multipolar, ii. 201. series winding, ii, 207. single-layer bipolar, ii, 197. tables of connections, ii, 204. use of an idle coil, ii, 208. Armatures: heating with direct current, ii. 136. measuring resistance of D. C.* I* 11- troubles in, i, 297. Auto-starter, i, 370. Auto- transformer, 426. i, 342. Automatic elevator oontroller, 11. 258. Automatic air-brake, ii, 287. Auxiliary phase in induction motors, i. 385. Balance, ampere, i, 82. Balance, magnetic. I. 170. Balance, torque, i, 112. 461 462 INDEX Balancer sets, i, 272. Ballistic galvanometer, caiibratioa of, 1, 181. Ballistic galvanometer, theory,' i, 179. Ballistic method of measuring flux, i, 172. Bar windings, ii. 190; ii, 132. Batteries, i, 390. dry, i. 392. Edison, i. 392. electromotive force of, i, 393. gravity cell, I, 391. Internal resistance, i, 394. Leclanch^ cells, i, 391. polarization and recovery, 1, 395. primary, !, 391. storage, i, 397. testing, i, 393. Battery boosters, i, 414. Behrend's split-field test, ii, 132. Bianchi slip meter, i, 379. Bismuth spiral, i, 187. Blackening of bulbs in incand^cent lamps, i, 218. Blondel hysteresimeter, i, 193. Blondel integrating photometer, i, 247. Blondel's opposition method, i, 32S. Blow-out coils, ii, 268, Bond tester, Conant, 1, 23. Bond tester. Holler, i, 21. Bonds, testing rail, i, 21; 1, 23. Boosters, i, 414. carbon-pile regulator, i, 416. difierential, i, 415. regulation by counter-e.m.f., i. 418. relay -operated regulator, i, 422. vibrating-contact regulator, i, 421. Brake, Prony, i, 282. Brake tests: induction motor, i, 381, 1, 389. series motor, i, 286. shunt motor, i, 285. synchronous motor, ii, 121. Brakes, magnetic, ii, 269. air. li, 284. Branched transmission lines, ii, 32. Bridge connection in car controllers, ii, 265. Bridge, Hoopes* conductivity, i, 31 Bunsen sight-box, 1, 212 Bus-bars, ii, 237. Gables, testing insulation of, ii, 58. Cadmium tester, i, 405. Calibration: A. C. ammeters with D. C. — A, C. stand- ards, 1, 67. A. C. voltmeters, i, 69. ammeters and voltmeters, i, 64. ammeters with potentiometer and stand- ard resistance, i, 82. D. C. ammeters, i, 65. D. C. voltmeters, i, 68; i, 81. ground detectors, ii, 56. indicating wattmetera, i, 94; i, 104. Candle-power, mean horizontal, i, 214. Candle-power, mean spherical, i, 223. Capacity, electrostatic, ii, 1. and inductance ia series, ii, 24. and inductance in parallel, ii, 19. and resistance in parallel, ii, 15. comparing, ii, 7; ii, 12. factors affecting, ii, 3. in A. C. circuits, ii, 12. influence in transmission lines, ii, 40, in practice, ii, 2. reactance, ii, 14. unit of, ii, 1. Capacity or storage batteries, i, 402. Carbon-pile booster regulator, i, 416. Carey-Foster method, i, 16. Carhart-Clark cell, i, 72. Car tests, ii, 278. acceleration and retardation, ii, 281. apparatus, ii, 279. determination of schedule, ii, 283. performance curves, ii, 280. Cells, standard, i, 71. Central-energy telephone systems, i, 451. Chain winding, ii, 193. Characteristics: excitation, of alternators, i, 354. excitation, of shunt generators, i, 256. excitation, of alternators, i, 354. load, of alternators, i, 348. no-load,, of alternators, i, 348. no-load, of shunt generator, i, 251. of induction motors, ii, 175; ii, 176. of storage batteries, i, 396; i, 404. voltage, of alternators, i, 352. Charging storage batteries, i, 409. Checking potentiometer resistances, i, 77. Circle diagram for induction motors, ii, 167; ii, 172; ii, 177; ii, 179. Circuit breakers, ii, 237. Circular mil. i, 4. Clark standard cell, i, 71. Coil winding, ii, 190. Color, effect on photometry of lamps, i, 222. Color of illuminants, ii, 319. Combination volt-ammeter, i, 55. Commercial tests of alternators and synchronous motors, ii, 129. Commercial tests on transformers, ii, 67. Common battery switchboard connec- tions, i, 454. Commutator troubles, i, 297. Commutator type integrating watt- meters, i, 101. Comparator, i, 69. Comparing resistances with potentiometer i, 82. Compensated motors, i, 293. Compensation for friction of meters, i, 103. Compensation for power in wattmeter i, 90. Compounding rotary converters, ii, 161. Compound winding, i, 256. Compound-wound motors, i, 287. INDEX iG-6 Conant bond tester, i, 23. Condensers: construction of, ii, 3. factors affecting capacity of, ii, 3. in A. C. circuits, ii, 13. in series and in parallel, ii, 5. Conductance, i, 9. Conductivity bridge, i, 31. Conductors, size of, in polyphase lines, ii, 113. Constant current, means for maintain- ing, i, 238. Constant-current transformer, i, 240. Constant power over transmission lines, ii, 37. Control and operation of storage batteries, i, 407. Controllers, Electric, ii, 244. connections in, ii, 247. crane, i, 435. drum-type, i, 436. electric car, ii, 260. elevator, ii, 250. experimental, ii, 249. field control, i, 433. , motor speed regulator, i, 434. Controllers, electric car: acceleration limit, ii, 271. blow-out coil, ii, 2G8. change from seri^ to parallel, ii, 264. cut-out switches, ii, 267. diagram of connections, ii, 266. drum-type, ii, 260. magnetic brake, ii, 269. multiple-unit control, ii, 272. reversing, ii, 267. shunting the fields, ii, 269. starting connections, ii, 262, Cooking utensils, electric, ii, 296. Cooling curves, ii, 70. Cooling curves, equations of, ii, 73. Copper, minimum in transmission lines, ii, 34. Core loss, i, 307. Core loss, measurement of, i, 189; i, 192; i, 197. Core-type transformers, i, 336. Counter-e.m.f. booster regulator, i, 418. Crane Controllers, i, 435. Cumulative compounding, i, 287. Current ratio in rotary converters, ii, 158. Current ratio in transformers, i, 337. Cut-out switches, ii, 267. Dampers in rotary converters, ii, 164. Dampers in synchronous machines, ii, 125. D. C. ammeters, calibration of, 65. D. C. switchboards, ii, 232. D. C. voltmeters, calibration of, i, 68. Dead linra, insulation measurements on, ii. 57. Decade arrangement of coils, i, 24. Delta connection, ii, 106. Dielectrics, disruptive strength of, ii, 84. Differential boosters, i, 415. Direct-current machinery: magnetic field in, i, 152. opposition runs on, i, 325. troubles in, i, 396. Efficiency and losses, i, 300. core loss and mechanical losses, i, 307. direct and indirect methods for deter- mining, i, 300. losses by retardation method, i, 314. machine driven electrically, i, 304. machine driven mechanically, i, 305. separation of losses, i, 306. Operating features, i, 249. compound windings, i, 256. excitation characteristics, i, 256. no-load characteristics, i, 251. operation in parallel, i, 263; i, 269. Disruptive strength of dielectrics, ii, 84. Distributing lines, ii, 48. drop in, with distributed load, ii, 49. experimental, ii, 50. fed from both ends, ii, 52. fed from one end, ii, 51. insulation measurements, ii, 54. location of faults, ii, 54. Distribution of light, i, 224. Double-layer armature windings, ii, 195. Dry batteries, i, 392. Drysdale permeameter, i, 178. Du Bois magnetic balance, i, 170. Duddell oscillograph, ii, 217; ii, 219. Duddell thermo-galvanometer, i, 70. Dynamometer, transmission, i, 284. Eddy currents: methods of measuring loss, i, 191. physical nature of, i, 190. Edison primary battery, i, 392. Effective current, i, 38. Efficiency: of alternators and synchronous motors, ii. 129 Efficiency. of D. C. machines, i, 300; i, 302. of series motors, i, 323. of transformers, i, 344. of machine driven electrically, i, 304. of machine driven mechanically, i, 305. methods of determining, i, 300. Electric batteries, i, 390. Electric heating, and welding, ii, 293. Electro-dynamometer, absolute, i, 84. Electro-dynamometer type instruments, i, 42 Electromagnets, i, 158. Electrostatic capacity, ii, 1. Electrostatic voltmeters, i, 49. Elevator controllers, ii, 250. automatic, ii, 258. mechanically operated, ii, 252. no n -auto ma tic, ii, 254. E. M. F., form of induced, ii, 191. E. M. F. of batteries, i, 393. End cell switches, ii, 222. Epstein core, loss tester, ii, 57. Equalizer, action of, i, 268. 464 INDEX Esterline permeameter, i, 185. Everslied ohmmeter, ii, 58, Ewing: double-bar method, i, 175. magnetic tester, i, 192. permeability bridge, i, 186. Exchange, telephone, i, 447. Excitation, and power factor of synchro- nous motors, ii, 122. Experimental armature frame, ii, 190. Experimental controller, ii, 249. Experimental lines, ii, 50. Exploring wires, i, 7. Extrapolation of heating curves, ii, 69; ii, 74. Faults, measurement and location of, ii, 54. Field control, i, 433. Field rheostats, capacity of, ii, 237. Fields of direct-current machines, i, 152. troubles, in, i, 29G. variation of speed with varying field, i, 279. Flatiron, electric, ii, 295; ii, 298. Flicker photometer, i, 220. Floating batteries, i, 412; i, 413. Flux, magnetic, i, 140. density and ampere turns, i, 147. density and voltage, i, 197. distribution of, in air-gaps, i, 156. in air, i, 166. maps of stray, i, 152. total, in armature and field, i, 153. Fluxmeter, Grassot, i, 142. Foot-candle, ii, 308, Fort Wayne arc lamp, i, 234. Four-wire system, i, 276. Frequency meters, ii, 125. Frequency meters: resonance or vibrating-rced, ii, 126. split phase, ii, 126. Friction, compensation for, in meters, 1, 103. Friction in meter pivots, i, 42. Galvanometer, ballistic: calibration of, i, 189. theory of, i, 179. Graphico-analytical separation of losses, f, 320. Grassot fluxmeter, i, 142. Gravity cells, i, 391. Ground detectors: calibration of, ii, 56. lamps and voltmeters as, Ii, 55. static, ii, 54. three-phase, ii, 55. Harmonics, expression for, ii, 224. Heat generated by alternating current, 1, 47. Heating and cooling curves: equations of, ii, 74. extrapolation of, ii, 69; ii, 74. of transformers, ii, 69. Heating, electric, ii, 293. conversion of watts to heat units, ii, 295. devices for, ii, 293. forms of elements, ii, 295. utensils, testing, ii, 296; ii, 297; ii, 298. Heat run on alternators, ii, 135; ii, 137. Heat run on transformers, ii, 71. Hemispherical intensity, i, 229. Hobart and Funga, temperature teat on . alternators, ii, 136. Holden -Esterline core-loss meter, i, 195. Holophane globes and reflectors, ii, 306. Hoopes' conductivity bridge, i, 31. Hopkinson method of testing alternators, i, 331. Hot-wire instruments, i, 45. Hunting of alternators and synchronous motors, ii, 124. Hunting of rotary converters, ii, 163. Hutchison method of testing alternators, !, 332, i, 333. Hysteresimeter, Blondel, i, 193. Hysteresis: and eddy current losses, i, 191. loop, i, 165. loss from B-H loop, i, 204. measurement of loss by mechanical torque method, i, 192. measurement of loss by wattmeter method, i, 197. physical nature of, i, 189. separation from eddy current loasea, i, 206. Idle coil in armature windings, ii, 209. Impedance, i, 123. Impedances in parallel, i, 132; i, 134. Impedances in series, i, 129; i, 132. Inaccuracy of wattmeters at low power factors, i, 92. Incandescent lamps: blackening of bulbs, i, 218. life and efficiency of, i, 257. photometry of, i, 208. tungsten lamps, i, 217. Indicating wattmeters, i, 87 (see wattmeters). Induced e.m.f., form of, ii, 191. •Inductance: and reactance, i, 117. and resistance, i, 117. in transmission lines, ii, 38. measuring, with Wheatstone bridge, 1, 138. physical conception of, i, 116. unit of, i, 117. Induction coil for telephones, i, 438. Induction localizers, ii, 65. Induction motor, i, 366. brake test of, i, 381. data sheets for tests, i, 380. losses in, i, 381. measuring frequency and speed, i, 375. measuring input to, i, 374. performance from losses, i, 383. performance tests, i, 373. revolving magnetic field in, i, 366; ii, 181. slip, i, 369. speed control, i, 371. starting devices, i, 369. stator and rotor, i, 367. stroboscopic slip meters, i, 375. ' three-phase motors on single-phase cir- cuits, i, 386. INDEX 465 Induction motora, special study* ii, 166. circle diagram, ii, 167. constructing circle diagram, ii, 172. exploring field with direct current, ii, 185. losses, graphical representation of, ii, 168. no-load characteristics, ii, 175. output and torque, ii, 169. proof of circle diagram, ii, 177: ii, 179. r^istance of windings, ii, 174. study of revolving nqagnetic field, ii, 181. single-phase induction motors, i, 384. action of, i, 384. auxiliary phase in, i, 385. brake test, i, 389. exploring field of, ii, 187. magnetic field in, ii, 186. performance of, from losses, i, 389. predetermination of performance, ii, 180. starting, i, 388. starting as repulsion motor, i, 387. Induction, mutual, i, 136. Induction-type instruments, i, 47; i, 113. Induction-type wattmeters, i, 95. Influence of globes, shades and reflectors on distribution of light, ii, 308. Instantaneous speeds, measuring, i, 314. Insulation measurements, ii, 54. on dead lines, ii, 57. on live lines, ii, 59. on low-tension lines, ii, 62. transformer for, ii, 82. Integrating photometers: for arc lamps, i, 248. for incandescent lamps, i, 226. Integrating wattmetera, see Watt-hour meters. Interior illumination, ii, 305. calculation of, ii, 309. curves of, ii, 310. effect of color of illuminant, ii, 319. measurement of, ii, 312. units of, ii, 308. use of reflectors, shades and globes, fi. 305. Intermediate standards, i, 67. Interpoles, i, 291. Iron, effect of, in reactance coils, !, 122. Iron loss by wattmeter method, i, 204. Iron, saturation in, i, 144. Kapp's diagram, ii, 45; ii, SO; ii, 149. Kelvin balance, i, 83. Kelvin double bridge, i, 29. Kelvin multicellular voltmeter, i, 50. Kintner electrostatic voltmeter, i, 60. Koepsel permeameter, i, 182. Kohlrausch bridge, i, 19. Lamps: influence of blacking of bulb, i, 218. life and efflciency of incandescent, i, 216. photometry of, i, 208; i, 243. standard, i. 213. Leakage coefficient, i, 155. Leakage, magnetic, i, 148. Leclanohd cells, i, 391^ Leeds & Northrup comparator, !, 69. Leeds & Northrup potentiometer, i, 75- Life of primary batteries, i, 396. Lifting electromagnets, i, 158. Lincoln motor, i, 292. Line-drop compensators, ii, 41. Lines, transmission, ii, 26. Localizers, induction, ii, 65. Losses in direct-current machines, t, 301. core loss and mechanical, i, 307, hysteresis and eddy currents, i, 319 in series motors, i, 322. Separation of losses: machine driven electrically, i, 309. machine driven mechanically, i, 313. retardation method, 1. 314; i, 318- separation of friction from iroii loss, i. 310. Losses in induction motors, i, 381. Luminometer, Marshall, ii, 313. Lummer-Brodhun sight-bo?, i, 218. Magnetic brakes, ii, 269. Magnetic fields of direct-current machines, i, 152. maps of stray flux, i. 152. measurement of flux in, i. 154. total flux in armature and field, i, 153. Magnetic flux, i, 140. in air, i, 166. influence of air-gap, i, 145. influence of length and cross-section of path, i, 146. measurement with ballistic galvanom- eter, i, 142. magnetic leakage, i, 148; i. 150; i. 155- magnetization curves, i. 164; i. 169; i, 171. i, 182; i, 185. Marshall luminometer, ii, 313. Matthews' integrating photometer, i, 226. Maximum demand indicators, i, 113; i. 115. Mean hemispherical intensity of light, i, 229. Mean horizontal candle-power, i, 214- Mean spherical intensity of light, i, 223* Measuring instantaneous speeds, i. 314. Mershon's A. C. line drop compensatQr. ii, 42. Moment of inertia of revolving parts, i, 317. Motorman's valve, ii. 289. Motor starters, i, 425. electrically operated, i. 428. multiple switch, i, 427. with field control, i, 433. with no-voltage release, i. 425. with overload release, i, 431. Motors, direct-current, i, 278. brake test of series, i, 286 brake test of shunt, i, 285. compensated variable speed, i, 293. compound, i, 287. field strength and speed, i, 279. Lincoln, i, 292. Stow, i, 292. two-commutator, i, 295. types of, i, 278. Multiple arc lamps, 1, 232. Multiple-unit control, ii, 272. 466 INDEX MuItipIe-unit details of operation, ii, 275. disposition of parts, ii, 275. principles of operation, ii, 273. Murray loop, ii, 63. Mutual induction, i, 136; i, 137. Nalder potentiometer, i, 80. National Electrical Code, ii, 321. Ness telephone system, i, 445. Norms of illumination, ii, 312. Ohm, i, 1. Ohmraeter, Evershed, ii, 58. Ohmmeter, Sage, i, 18. Ohm's law, i, 1. Opposition runs: Blondel's method, i, 32S. classification of, i, 327. Hopkinson method, i, 331. Hutchison method, i, 332. mechanical analogy, i, 326. on alternators, ii, 131; ii, 137. on direct-current machinery, i, 325. on series motors, i, 334. on transformers, ii, 68. Optimistic limit of alternator regulation, ii, 143. Oscillograph, ii, 216. determining A. C. wave form with, ii, 222. Duddell, ii, 219. student's, ii, 220. Otis elevator, ii, 251. Overload release, i, 431. Parallel operation of alternators, i, 357. Parallel operation of D. C. generators, i, 263; i, 269. Party telephone lines, i, 455. Pellat absolute electro-dynamometer, i, 84. Performance curves of alternators, i, 351. Permeability, i, 144. Permeability tests, i, 164. ballistic m.ethod, i, 172. divided-bar method, i, 174. Ewing double-bar method, i, 175. permeameters, i, 167; i, 176; i, 178. ring method, i, 173. steady deflection method, i, 182. tractional method, i, 167. Pessimistic limit of alternator regulation, ii, 143. Phase-angle and power factor, i, 127. Phase-angle, correction for, i, 110. Phase transformation, ii, 114. Photometry: of arc lamps, i, 243. of incandescent lamps, i, 208. construction of photometers, i, 241. flicker photometer, i, 220. integrating photometers, i, 226. the photometer, i, 208. Weber photometers, ii, 314. with lights of different color, i, 222. Picou permeameter, i, 177. Pivots, friction in, i, 42, Polarization of batteries, i, 395. Polyphase boards, i, 56; i, 57; i, .58. Polyphase systems, ii, 89. electrical relations in, ii, 89. size of conductors, ii, 113. transformation to single-phase, ii, 118. Portable testing sets, i, 27. Potentiometers, i, 73, checking resistances of, i, 77. Leeds & Northrup, i, 76; i, 78. Nalder, i, 80. study of a simple, i, 74. Potier's diagram, ii, 149. Power-factor, i, 88. diagram for finding, ii, 46. influence of, in transmission lines, ii, 35. influence of, upon drop in alternators, i, 350. Power-factor meter, i, 97, i, 98. Power relations with impedances in series, i, 132. Power relations with resistance and reactance in series, i, 128. Predetermining regulation: of alternators, ii, 145. of transformers, ii, 75. of transmission lines, ii, 44. Primary and secondary standards, i, 64. Primary batteries, i, 391. Prony brake, i, 282. Quarter phase, mesh-connected, ii, 94. Quarter phase, star-connected, ii, 95. Radiator, electric, ii, 297. Hail bonds, i, 21. Railway work, electric, ii, 260. Ratio of voltages and currents in trans- formers, i, 337. Reactance and resistance: capacity reactance, ii, 14. combinations, i, 123. in A. C. circuits, i, 116. power relations, i, 128. reactance and inductance, i, 117. resistance and inductance, i, 117. triangle of voltage drops in, i, 127, Reactance, i, 116. coil with iron, i, 123. coil with resistance, i, 125. experimental determination of, i, 119. factors affecting value of, i, 120. of coil without iron, i, 122. phase-angle and powei'-f actor, i, 127. Recording instruments, i, 59; i, 63. ammeters, i, 63. operating on relay principle, i, 61. voltmeters, i, 62, Recovery of primary batteries, i, 395. Reduction factor, spherical, i, 223. Regulation of alternators, ii, 138. at power factors other than zero, ii, 147. at power factor zero, ii, 138. by split-fleld test, ii, 140. from synchronous motor load,- ii, 139. Kapp's diagram applied to, ii, 149. optimistic and pessimistic limits, of, ii, 143. Potier's diagram applied to, ii, 149. Regulation of transformers, ii, 75. INDEX 467 Regulation of traQsmission lines, ii, 27; ii, 44. Regulator, Tirrell, i, 261; i, 356. Regulators for boosters, i, 418; i, 421; i, 416. Regulators, motor speed, ii, 244. Relations in polyphase systems, ii, 89; ii, 94. Relay principle, instruments operating on, i, 61. Reluctance, apparent, ii, 146. Reluctance, factors affecting, i, 146. Remote-control switchboards, ii, 243. Remote-control switches, i, 430. Repulsion motor, induction motor starting as, i, 387. Resistance: checking potentiometer resistances, i, 77. comparing with the potentiometer, i, 82. equivalent primary and secondary, ii, 76. factors, affecting, i, 3; i, 4. influence of temperature, i, 5. in series and in parallel, i, 8. in series-parallel, i, 9. Measuring resistances: by Carey-Foster method, i, 16. by drop-of -potential method, i, 2. of D. C. armatures, i, 11. of rail bonds, i, 21. of very small resistances, i, 29. substitution method, i, 11; i, 12. with Kohlrausch bridge, i, 19. with Sage ohmmeter, i, 18. with Wheatstone bridge, i, 13. of zinc sulphate, i, 20. resistance of a conductor, i, 1. specific resistance, i, 4. temperature coefficient, i, 5; i, 6. Resistance, inductance and capacity in tele- phone circuits, i, 458. Resistance of primary batteries, i, 394. Resistance of storage batteries, i, 405. Resonance, electric, ii, 16. current, ii, 17. vector diagrams of, ii, 22. voltage, ii, 20. Resonance frequency meter, ii, 126. Retardation method, i, 314; i, 315; i, 328. Reversing railway motors, ii, 267. Revolving field in induction meters, ii, 78. Revolving field in induction motors, i, 366. ii, 181. Revolving field, instantaneous values of, ii, 184, Ring lines, ii, 53. Roller bond tester, i, 21. Rotary converter, ii, 152. armature connections in, ii, 153. compounding, ii, 161. dampers, ii, 164. hunting, ii, 163. Rotary converters: polyphase, ii, 160; ii, 161. ratio of currents, ii, 158. ratio of voltages, ii, 156. single-phase, ii, 159; ii, 160. starting, ii, 154. Rotary converters, voltage regulators used with, ii, 163. Rotator, universal, i, 212. Rotor in induction motors, i, 367. Rousseau diagram, i, 224. Safety of electric plants, ii, 321. Sage ohmmeter, i, 18; i, 19, Sangamo meter, i, 106. Saturation factor, i, 144. Saturation in iron, i, 144. Schedules for cars, ii, 283. Scott's system of phase transformation, ii, 115. Self-excitation, i, 250. Separation of Hysteresis and eddy current losses, i, 206. Separation of losses in D. C. machine, i, 306. analytical method, i, 319. graphi co-analytical, i, 320. in series motors, i, 322. Series and decade arrangement of coils, i, 28. Series arc lamps, i, 235; i, 237. Series armature windings, ii, 208. Series motors: brake test, i, 286. • efficiency from losses, i, 323. opposition runs, i, 334. separation of losses in, i, 322. Series-parallel resistances, i, 9. Series windings in D. C. generators, i, 259. Shadowgraphs, ii, 298. Shell-type transformers, i, 336. Short-circuit test on transformers, ii, 78. Shunts, i, 40. Shunt generators: no-load characteristics of, i, 251. voltage drop and regulation, i, 252. Shunt motor brake test, i, 285. Shunting railway motor fields, ii, 269. Sight-box, i, 212; i, 218. Signalling in telephony, i, 440. Six-phase system, ii, 116. Slide wire Wheatstone bridge, i, 14. Slip in induction motors, i, 369. Slip meters, i, 375. Soldering iron, electric, ii, 297. Specific resistance, i, 4. Speed control of D. C. motors, i, 281. Speed control of induction motors, i, 371. Split-field test of alternators, ii, 132; ii, 140. Split-phase frequency meter, ii, 126. Squirrel-cage rotor, i, 368. Standards: cells, i, 71. fluid, i, 20. lamps, i, 213. Standards. low resistance, i, 30. of illumination, ii, 318. primary and secondary, i, 64. Starting devices for induction motors, ii 369. Static ground-detector, ii, 54. Stator of induction motors, i, 367, 468 INDEX Storage batteries, ii, 198. boosters, i, 414. capacity, i, 402. charge and discharge characteristics, !, 404, charging, i, 408; i, 409. construction and chemical action, i. 399. end-cell switches, i, 409. floating batteries, i, 412. in alternating-current plants, i, 423. internal resistance, i, 405. operation and control, i, 407. testing, i, 403. voltage by cadmium tester, i, 405. voltage during charge and discharge, i, *31. Stow motors, i, 256. Stroboscopic slip meters, i, 375. Substitution method of measuring resistances, i, 11. Switchboards, ii, 232. Altern ati n g-current : for one alternator, ii, 238. for two or more alternators, ii, 241, Direct-current: for one generator, ii, 232. for two or more generators, ii, 234. miscellaneous boards, ii, 238. size of apparatus on, ii, 230. Synchronism indicators, i, 300. Synchronizing, i, 362. Synchronizing connections, ii, 242. Synchronizing lamps, i, 359. Synchronous motors: brake test, ii, 121. excitation and power factor, ii, 122. hunting of, ii, 124. operating features, ii, 120. starting, ii, 120. V-curves, ii, 124. vector diagram, Ji, 122. Synchronous motors and alternatora, I, 347. remote -control boards, ii, 243. synchronizing connections, ii, 242. voltmeter connections, ii, 242. Tables for wave analysis, ii, 225. Telephone switchboards, i, 448. Telephony, i, 437. adjusting transmitters and receivers, I, 439. classification of installations, i, 439. house telephones, i, 443. Telephony: induction coil, i, 438. intercommunicating telephones, i, 444, magneto-telephone connections, i, 442, magneto-telephone exchange, i, 447, ringer and magneto, i, 441. signalling, i, 440. switchboard connections, i, 448. transmitter, i, 437. Central energy systems: battery connections, i, 451. common battery switchboard connections, i, 454. connecting subscribers, i, 452. Telephony, party lines, i, 455. resistance, inductance and capacity in lines, i, 458. retardation coils, i, 451, Temperature co-effiolent, I, 5; i, 6. Temperature, determination of in windings, 1,6. Temperature rise of alternators, ii, 135. , Temperature test, Hobart & Punga, ii, 136. Testing sets, i, 27. Thermo -galvanometer, i, 70. Thompson permeameter, i, 167. Thomson -Houston arc light machine, I, 239; i. 240. Thomson integrating wattmeter, i, 101. Three-phase systems, ii, 96. DeU3.-connections, ii, 106. measuring power in Y-conneotion, il, 100; ii, 101. r^istance in neutral wire, ii, 90. T-connection, ii, 111; ii, 193. three-phase to six-phase transformation, ii, 116. V-connection, ii, 108. Y-connection, current relations, ii, 97, Y-connection, voltage relations, ii, 98. Three- voltmeter method, i, 131, Three-wire systems, i, 270. effects of unbalancing, i, 273. methods of dividing voltage. I, 271. motors on, i, 293. study of symmetrical, i, 275. study of unaymmetrical, i, 276. unsymmetrical, i, 296. Tirrill regulator, i, 261; i, 355. Torda-Heymann, predetermining alternatoi regulation, ii, 145. Torque and friction in watt-hour meters, i, 111. Torque balance, i, 112. Torque in electro-dynamometer instruments, i, 42. Tractional method of measuring perme- ability, i, 167, Tractive electro-magnets, i, 158. Transformer, i, 336. a testing transformer, ii, 82. auto-transformer, i, 342. commercial tests, ii, 67. constant-current, i, 240. cooling and heating curves, ii, 69; fl, 73. core-type and shell-type, i, 336. efficiency, i, 345. heat run on, ii, 71. loading, i, 339. opposition tests on, ii, 68. phase transformation, ii, 114. predetermination of regulation, ii, 75. ratio of voltages and currents, i, 337, regulation from short-circuit testa, ii, 78- testing insulation, ii, 82. temperature rise, ii, 67. transferring resistances, ii, 76. voltage drop in, i, 338. INDEX 469 Transformer, voltage regulation, ii, 75; welding, ii, 301. Transmission dynamometer, i, 284. Transmission lines, ii, 26. alternating-current, ii, 34. at constant power, ii, 37. branched, ii, 32. experimental, ii, 29. influence of capacity, ii, 40. influence of inductance, ii, 38. influence of power factor, ii, 35. influence of voltage and of cross-sectioD. ii/31. regulation, ii, 27; ii, 30. voltage drop, ii, 26; ii, 45. Triple valve, ii, 290. Troubles in D. C. machines: armature, i, 297. commutator, i, 297. field, i, 296. locating, i, 298. Tun^ten lamps, i, 217. Two-commutator motor, i, 295. Two-phase systems, ii, 91. four-wire system, ii, 91. quarter-phase, mesh connection, ii, 95. quarter-phase, star connection, ii, 94. three-wire system, ii, 91. Ulbricht's integrating photometer, i, 227. Variable speed drive, i, 291. Varley loop, ii, 63. V-connection, ii, 108. V-curves of synchronous motors, ii, 124. Vector diagrams: alternating-current wave analysis, ii, 224. alternators, i, 351; i, 353; ii, 148. capacity and inductance (resonance), ii, 15; ii, 19; ii, 22; ii, 24; ii, 166. compounding rotary converters, ii, 161. induction motors, i, 380; ii, 167; ii, 170; ii, 178; ii, 179. polyphase circuits, relations in, ii, 92; ii, 93; ii, 96; ii, 98; ii, 99; ii, 100; ii, 107; ii, 112. resistance and inductance, i, 124; i, 126; i, 130; i, 133; i, 134: i, 136. synchronous motors, ii, 122; ii, 123. transformers, ii, 99; ii, 81, transmission lines, ii, 35; ii, 36; ii, 39; ii, 45. Vibrating-contact booster regulator, i, 421. Vibrating-reed slip meters, i, 377. Voltage and current ratios in transformers, i. 337. Voltage and flux density, i, 199, Voltage drop: in distributing lines, ii, 49. in resistance and reactance, i, 127- in shunt generators, i, 262. in transformers, i, 338. in transmission lines, ii, 26. Voltage ratios in rotary converters. Ii, 156. Voltage regulation of rotary converters, ii, 163, Voltmeters, i, 34. as ground detectors, ii, 55. calibration of A. C. i, 69, calibration of D. C. i, 68; I, 80. connections, ii, 242. high-tension, i, 50 line-drop compensators, ii, 41, range of, ii, 237. recording, I, 62. Volt-ammeters, i, 55. Voltmeter plug, ii, 236. Watt-hour as unit of consumption, 99= Watt-hour meters, i, 99. commutator type, i, 101; i, 104. correction for phase angle, i, 110 Induction-type, i, 107; i, 113. polyphase, i, 109. Sangamo, i, 106. Thomson, i, 101. torque and friction, i. 111. rating of, ii, 237. Wattmeters, i, 87. compensation for power in, i, 90. electro-dynamometer type, i, 89; I, 94. inaccuracy at low power factors, i, 92. indicating, i, 87. induction, i, 95. Integrating, see Watt-hour meters. Watt-ratio curve, ii, 102. Wave form, alternating-current, ii, 210. analysis of, ii, 222. analyzing tables, ii, 225; ii, 228; ii, 231. by point-to-point method, ii, 211; ii, 212 by oscillograph, ii, 216; ii, 222. general equations of. ii, 223; ii. 227. harmonics, ii, 224. Weber photometer, ii, 314. Welding, ii, 293; ii, 298; ii, 300; ii, 301. Westinghouse air-brake, ii, 284. Westinghouse power-factor meter, i, 97. Wheatstone bridge; i, 13. Carey-Foster method, i, 16. Kelvin double bridge, i, 29. Kohlrausch bridge, i, 19. measuring inductance with, i, 138. measuring resistance with, i, 16. plug-type bridge, i, 24. slide-wire, i, 14. Wright maximum-demand indicator: Y-connection, ii, 97. current relations in, ii, 97. measuring power, ii, 100. unbalanced load, ii, 98; ii, 104. voltage relations in, ii, 98. with inductive load, ii, 105. Zero, power-factor regul tion at, ii, 138. Zinc sulphate, resistance of, i, 20. 