| Cooperating organisations |
|
6 | (1) |
| Acknowledgements |
|
7 | (1) |
| Preface |
|
8 | (1) |
| Introduction |
|
9 | (2) |
|
Chapter 1 The regulations concerning protection against overcurrent |
|
|
11 | (8) |
|
|
|
11 | (1) |
|
1.2 Nature of overcurrent and protection |
|
|
12 | (1) |
|
1.3 Statutory requirements |
|
|
13 | (1) |
|
1.4 Omission of protection |
|
|
13 | (1) |
|
|
|
13 | (1) |
|
1.6 Duration of overcurrent |
|
|
14 | (1) |
|
1.7 Coordination and discrimination |
|
|
14 | (5) |
|
Chapter 2 Protection against overload |
|
|
19 | (24) |
|
|
|
19 | (1) |
|
|
|
19 | (2) |
|
2.3 Selection of protective device |
|
|
21 | (2) |
|
2.4 Selection of conductor cross-sectional area with overload protection |
|
|
23 | (1) |
|
2.5 Omission of protection against overload current |
|
|
24 | (5) |
|
|
|
29 | (1) |
|
2.7 Avoidance of unintentional operation of circuit-breakers |
|
|
30 | (3) |
|
2.8 Current ratings of low voltage assemblies (switchboards, panel boards, distribution boards, etc.) |
|
|
33 | (1) |
|
2.9 Cables for star-delta starters |
|
|
33 | (2) |
|
|
|
35 | (2) |
|
|
|
37 | (3) |
|
|
|
40 | (1) |
|
2.13 Mineral insulated cables and ring final circuits |
|
|
40 | (3) |
|
Chapter 3 Protection against fault current |
|
|
43 | (16) |
|
3.1 Types of fault to be considered |
|
|
43 | (1) |
|
3.2 Nature of damage and installation precautions |
|
|
43 | (3) |
|
3.3 Fault impedance and breaking capacity of protective device |
|
|
46 | (2) |
|
3.4 Short-circuit rating of low voltage assemblies (switchboards, panel boards, distribution boards, etc.) |
|
|
48 | (1) |
|
3.5 Position of fault current protection and assessment of prospective current |
|
|
48 | (4) |
|
3.6 Omission of fault current protection |
|
|
52 | (2) |
|
3.7 The use of one device for both overload and fault current protection |
|
|
54 | (1) |
|
|
|
54 | (4) |
|
|
|
58 | (1) |
|
Chapter 4 Determination of fault current |
|
|
59 | (6) |
|
4.1 Determination of fault current by enquiry |
|
|
59 | (2) |
|
4.2 Measurement of fault current |
|
|
61 | (1) |
|
4.3 Calculation of fault current |
|
|
62 | (1) |
|
|
|
63 | (2) |
|
Chapter 5 Equations for the calculation of short-circuit current |
|
|
65 | (10) |
|
5.1 General equation for fault current |
|
|
65 | (1) |
|
5.2 Single-phase, line to neutral fault |
|
|
66 | (1) |
|
5.3 Conductor temperature and resistance |
|
|
67 | (3) |
|
5.4 Single-phase circuits |
|
|
70 | (1) |
|
5.5 Line-to-line short-circuit |
|
|
71 | (1) |
|
5.6 Three-phase short-circuit |
|
|
72 | (3) |
|
Chapter 6 Equations for the calculation of earth fault current |
|
|
75 | (10) |
|
|
|
75 | (1) |
|
6.2 TN-S and TN-C-S systems |
|
|
75 | (2) |
|
6.3 Cable enclosure used as a protective conductor |
|
|
77 | (6) |
|
|
|
83 | (2) |
|
Chapter 7 Selection of conductor size |
|
|
85 | (8) |
|
|
|
85 | (1) |
|
7.2 Overload and short-circuit protection by a single device |
|
|
85 | (1) |
|
|
|
85 | (1) |
|
|
|
86 | (1) |
|
7.5 Energy let-through characteristics |
|
|
86 | (2) |
|
7.6 Duration of short-circuit current |
|
|
88 | (1) |
|
7.7 Status of adiabatic equations |
|
|
89 | (1) |
|
7.8 Alternative values of k |
|
|
89 | (1) |
|
7.9 Appendix 4 of BS 7671 |
|
|
90 | (3) |
|
Appendix A Calculation of reactance |
|
|
93 | (6) |
|
|
|
93 | (1) |
|
A2 Line to neutral, single-phase faults |
|
|
93 | (1) |
|
A3 Line-to-line, single-phase, short-circuit |
|
|
94 | (1) |
|
A4 Three-phase short-circuit |
|
|
95 | (1) |
|
|
|
96 | (3) |
|
Appendix B Calculation of k for other temperatures |
|
|
99 | |
|
|
|
99 | |
| Index |
|
101 | |
