viii CONTENTS 



CHAPTER V 



PACKS 



31. General conditions to be satisfied by alternate-current instruments 32. 

 Hot-wire instruments 38. Electrostatic instruments for low voltages 

 34. Methods of extending range of low-reading electrostatic voltmeters 

 35. High- voltage electrostatic instruments 36. Wattmeters 37. 

 Power-factor indicators 38. Oscillographs 60-77 



CHAPTER VI 



39. Dynamo used as alternator 40. Constructional differences between 

 dynamos and alternators 41. Standard type of alternator 42. Con- 

 struction of turbine-driven alternator 43. Armature windings of alter- 

 nators 44. Calculation of armature e.m.f. Effect of varying length of 

 polar arc 45. Effect of varying number of slots 46. General formula 

 for e.m.f. of alternator 47. Armature reaction in alternators 48. 

 Walker compounded alternator 78-99 



CHAPTER VII 



49. Transformers. Ratio of transformation 50. Constant potential trans- 

 former 5r. Examples of transformer construction 52. Calculation of 

 e.m.f. induced in transformer winding 53. Losses in transformer. 

 Hysteresis loss 54. Calculation of eddy-current loss in core. Discrepancy 

 between calculated and observed core losses 55. Copper losses. Best 

 dimensions of core 56. Heating of transformers 57. Star and mesh 

 connections for transformers. Comparison of single-phase and polyphase 

 transformers for polyphase circuits 58. Auto-transformer or compensator 

 59. Phase transformers 60. Choking coils .... 100-114 



CHAPTER VIII 



61. Induction motors. Squirrel-cage rotor 62. Rotor windings 63. 

 Starting resistances for rotors. Internal short-circuiting and brush-lifting 

 gear 64. Lewis induction motor 65. Example of induction motor. 

 Variation of torque with position of rotor 66. Asymmetry of hemi-tropic 

 stator winding with odd number of pole-pairs. Method of obtaining 

 symmetry 67. General characteristics of induction motor. Air-gap 

 length. Effect of rotor eccentricity 115-126 



CHAPTER IX 



68. Alternator used as motor. Synchronism 69. Stability of synchronous 

 motor 70. Magnitude and phase of current for various conditions of 

 load. Overload capacity 71. V- urves f synchronous motor 72. 

 Condenser action of over-excited synchronous motor. Use of synchronous 

 motor as compensator 73. Hunting of synchronous motor 74. Pre- 

 vention of hunting 75. Starting of synchronous motor 76. Paralleling 

 or synchronization of alternators 77. Everett-Edgcumbe rotary syn- 

 chronizer 78. Siemens and Halske three-phase synchronizer 79. 

 Parallel running of alternators. Starting of new machines . . 127-150 



