Electrical calculations: Vol 5

Synopsis:

The book demonstrates to the electrical engineer on how to size wireways such as conduit, ducting, trunking, and cable trays for carrying of cables and conductors. It also covers cable sizing and selection, fault level calculations based on the per unit method.

The book is presented in a Q&A format for ease of understanding and application.

Table of Contents

1. List of figures. v
2. List of tables. v

iii.   SI units basic. vi

1. Derived units. vi
2. Accepted non-SI units. vii
3. Electrical formulas. vii

vii.      Standard electrical unit of measure. viii

viii.     Multiples and sub multiples. ix

1. Copper cable electrical properties. x
2. Cable properties – Impedance. 1
3. Impedance of parallel cables. 1
4. Loading capacity of cable. 1
5. Single phase voltage-drop. 2
6. Three phase voltage drop. 2
7. Approximately mass of cable. 3
8. Cable spacing. 3
9. Power loss in single phase cable. 4
10. Power loss in a three-phase cable. 4
11. Area of trunking and ducting. 5
12. Area of conduit 5
13. Volume of trunking. 5
14. Volume of sleeve pipe. 6
15. Cable trenching. 6
16. Usable area of trunking. 7
17. Conductor fill in trunking. 7
18. Sizing of trunking. 8
19. Conductor fill in trunking. 10
20. Cable tray sizing 1. 11
21. Cable tray sizing 2. 13
22. Cable tray sizing 3. 15
23. Cable ladder sizing 4. 16
24. Cable ladder layout 17
25. Voltage imbalance. 18
26. Cable selection 1. 19
27. Cable selection 2. 20
28. Balanced load voltage drop. 22
29. Determine supply voltage. 23
30. Cable derating/correction factors in ground. 23
31. Cable derating/correction factors in air. 24
32. Cable derating factor for neutral imbalance. 25
33. Cable derating factor for harmonic currents. 25
34. Sustained current carrying capacity of a cable buried in ground. 26
35. Sustained current carrying capacity of the cable in air. 26
36. Correction factor for group of cables of different sizes in conduit, cable trunking or cable ducting 27
37. Calculation of voltage drop due to specific loads. 28
38. Alternative calculation of voltage-drop. 31
39. Current loading of a cable considering derating 1. 31
40. Current loading of a cable considering derating 2. 32
41. Fault level calculations using per unit method example 1. 32