Electrical Applications 2 (eBook)

Front Cover 1
Electrical Applications 4
Copyright Page 5
Table of Contents 6
PREFACE 10
CHAPTER 1. TRANSMISSION AND DISTRIBUTION OF ELECTRICAL ENERGY 12
Synchronous generators 12
Economics of generation and transmission 12
Overhead lines 15
Comparison between overhead lines and underground cables 16
Switchgear, definitions and uses 18
Substation layout and equipment 18
The three-phase system 20
Industrial installations 21
Distribution systems 23
Distributor calculations 24
Problems for Section 1 29
CHAPTER 2. REGULATIONS 32
Safety and regulations 32
The Electricity Supply Regulations 32
Electricity (Factories Act) Special Regulations 33
Substations and transformers 33
The Institution of Electrical Engineers' Regulations for Electrical Installations 34
The Health and Safety at Work Act 36
Comparison between the scopes of the regulations 38
Problems for Section 2 38
CHAPTER 3. TARIFFS AND POWER FACTOR CORRECTION 39
Generation and transmission costs 39
Power factor 40
Maximum demand 40
Diversity factor 41
Load factor 41
Cost of electrical energy 41
Problems for Section 3 47
CHAPTER 4. MATERIALS AND THEIR APPLICATIONS IN THE ELECTRICAL INDUSTRY 50
Conductor materials for overhead lines and underground cables 50
Performance of insulating materials 51
Insulating materials for cables 53
Cable construction 54
Materials used in electronic circuits 56
Conductor screening and coaxial cable 56
Printed circuits 57
Circuit damage due to overcurrents 60
Heating of cables 61
Permitted volt-drops in cables 61
Effect of ambient temperature on rating 62
Cables in ducts or in close proximity 63
Heat sinks 65
The insulation of overhead lines 65
Eddy current and hysteresis losses 66
Magnetic materials 67
Minimisation of losses 70
Permanent magnets 71
Magnetic screening 71
Problems for Section 4 71
CHAPTER 5. TRANSFORMERS 74
Principle of action of the transformer 74
EMF equation 75
The single-phase transformer 75
The three-phase transformer 78
Transformer cooling 81
The auto-transformer 82
Advantages of the auto-transformer over the double-wound transformer 83
Disadvantages of the auto-transformer 84
Current transformers 84
Voltage or potential transformers 87
Measurement of power and power factor 88
Problems for Section 5 89
CHAPTER 6. DC MACHINES 90
Principle of action 90
Power, force and torque 91
Fleming's rules 92
The action of the commutator 92
The ring-wound armature 94
The lap winding 95
The wave winding 97
The EMF and speed equations 98
DC machine connections 99
The DC motor 100
DC motor starters 105
The DC generator 110
Armature reaction 111
Losses in DC machines 114
The power flow diagram 115
Problems for Section 6 116
CHAPTER 7. ILLUMINATION 118
Lighting standards 119
Luminance and luminous intensity 120
The lumen and the steradian 121
The inverse square law 122
The cosine law 122
The polar diagram 123
Reflection and refraction of light 125
Use of the polar diagram 126
Indirect illumination of a surface 128
Types of lamp 130
Types of luminaire 134
Daylighting 135
Problems for Section 7 136
CHAPTER 8. FUSE PROTECTION 139
Fault level 139
Fuse protection 140
Operation of fuses 140
The semi-enclosed rewireable fuse 140
The high rupturing capacity (HRC) fuse 141
Fuse characteristics 143
Problems for Section 8 146
SOLUTIONS TO PROBLEMS 148
Section 1 148
Section 3 148
Section 4 148
Section 5 149
Section 6 149
Section 7 149
Section 8 149
INDEX 150