viii CONTENTS 



CHAPTER III 



PAGE 



ALTERNATING-CURRENT INSTRUMENTS AND MEASUREMENTS 51 



ro-dvnamometer Type Instruments 51 



27. The Siemens Dynamometer 52 



28. The Indicating Electro-dynamometer 52 



29. The Electro-dynamometer Voltmeter 53 



30. Inclined-coil Voltmeters 54 



31. Dynamometer Ammeters 55 



32. The Wattmeter 55 



33. Wattmeter Connections 57 



Iron-vane Instruments 61 



34. Voltmeters 61 



35. Ammeters 63 



36. Hot-wire Instruments 63 



37. Alternating-current Watthour Meter 63 



38. Frequency Indicators 68 



39. Power-factor Indicators 69 



40. Synchroscope 71 



41. The Oscillograph 72 



CHAPTER IV 



POLYPHASE SYSTEMS 76 



42. Reasons for the Use of Polyphase Currents 76 



43. Symbolic Notation 77 



44. Generation of a Three-phase Current 79 



45. Y-connection 80 



46. Delta-connection 83 



Methods of Measuring Power in Three-phase System 87 



47. Three-wattmeter Method 87 



48. Two-wattmeter Method 89 



Two-phase Systems 93 



49. Quarter-phase or Two-phase Systems (Sometimes Called 



Four-phase). 



CHAPTER V 



THE ALTERNATOR 99 



50. Rotating-field Type 99 



Alternator Windings 100 



51. General Principles 100 



52. Single-phase Windings 101 



53. Two-phase Windings 104 



54. Two-phase Lap Winding . 106 



55. Three-phase Windings 106 



