BS 5622-1:1979

Foreword
Cooperating organizations
Chapter I: General considerations
Section one - Scope and object
1. Scope
2. Object
Section two - Definitions
3. Nominal voltage of a three-phase system
4. Highest voltage of a three-phase system
5. Highest voltage for equipment
6. External insulation
7. Internal insulation
8. Indoor external insulation
9. Outdoor external insulation
10. Self-restoring insulation
11. Non-self-restoring insulation
12. Type test
13. Routine test
14. Isolated neutral system
15. Resonant earthed system (system earthed through
     an arc-suppression coil)
16. Earthed neutral system
17. Earth fault factor
18. Overvoltage
19. Phase-to-earth per unit overvoltage (p.u.)
20. Phase-to-phase per unit overvoltage (p.u.)
21. Switching overvoltage
22. Lightning overvoltage
23. Statistical switching (lightning) overvoltage
24. Conventional maximum switching (lightning) over-
     voltage
25. Temporary overvoltage
26. Statistical switching (lightning) impulse withstand
     voltage
27. Conventional switching (lightning) impulse
     withstand voltage
28. Rated switching (lightning) impulse withstand
     voltage
29. Rated short duration power-frequency withstand
     voltage
30. Rated insulation level
31. Statistical safety factor
32. Conventional safety factor
33. Protection level of a protective device
34. Protection factors of a protective device
Section three - Basic principles of insulation
co-ordination
35. Insulation co-ordination
36. Voltage stresses and other factors affecting
     insulation
37. Ranges of highest voltages for equipment
38. Delectric tests
38.1 Types of dielectric tests
38.2 Selection of the dielectric tests
39. Co-ordination for voltages under normal operating
     conditions and for temporary overvoltages
40. Co-ordination for switching and lightning over-
     voltages
40.1 Choice of the procedure
40.2 Statistical procedure
40.3 Conventional procedure
Chapter II: Standard insulation levels for equipment in
Range A
41. General indications
42. Tables of standard insulation levels
Chapter III: Standard insulation levels for equipment in
Range B
43. General indications
44. Table of standard insulation levels
45. Choice of the insulation level
Chapter IV: Standard insulation levels for equipment in
Range C
46. General indications
47. Table of standard insulation levels for highest
     voltage range for equipment equal to or greater
     than 300 kV
48. Rated switching impulse withstand voltage
49. Rated lightning impulse withstand voltage
Chapter V: General testing procedure
50. General
51. Switching and lightning impulse withstand tests
52. 50% disruptive discharge test
53. Fifteen-impulse withstand test
54. Conventional impulse withstand test
55. Short duration power-frequency voltage withstand
     tests

Definitions, basic principles, standard insulation levels and general testing procedures for equipment for 3-phase a.c. systems having a highest voltage for equipment above 1 kV. Except for some definitions, applies only to phase-to-earth insulation.