BS 923-1:1990

Committees responsible
National foreword
Section 1: General
1. Scope
2. Object
Section 2: General Definitions
3. Impulses
3.1 Lightning and switching impulses
4. Characteristics related to disruptive discharge
      and test voltages
4.1 Disruptive discharge
4.2 Characteristics of the test voltage
4.3 Disruptive discharge voltage of a test object
4.4 Statistical characteristics of disruptive discharge
      voltages
4.5 Withstand voltage of a test object
4.6 Assured disruptive discharge voltage of a test
      object
5. Classification of insulation in test objects
5.1 External insulation
5.2 Internal insulation
5.3 Self-restoring insulation
5.4 Non-self-restoring insulation
Section 3: General requirements relating to test
procedures and test objects
6. General requirements for test procedures
7. General arrangement of the test object
8. Dry tests
9. Wet tests
9.1 Standard wet test procedure
9.2 Traditional procedures for wet tests with
      alternating voltages
10. Artificial pollution tests
10.1 Preparation of test object
10.2 Test procedures
10.3 Degree of pollution
11. Atmospheric conditions
11.1 Standard reference atmosphere
11.2 Atmospheric correction factors
11.3 Wet tests, test under artificial pollution and
      combined tests
11.4 Conflicting requirements for testing internal
      and external insulation
11.5 Measurement of humidity
Section 4: Tests with direct voltage
12. Definitions for direct voltage tests
12.1 Value of the test voltage
12.2 Ripple
13. Test voltage
13.1 Requirements for the test voltage
13.2 Generation of the test voltage
13.3 Measurement of the test voltage
13.4 Measurement of the test current
14. Test procedures
14.1 Withstand voltage tests
14.2 Disruptive discharge voltage tests
14.3 Assured disruptive discharge voltage tests
Section 5: Tests with alternating voltage
15. Definitions for alternating voltage tests
15.1 Definitions for alternating voltage tests
15.2 Peak value
15.3 R.M.S. value
16. Test voltage
16.1 Requirements for the test voltage
16.2 Generation of the test voltage
16.3 Measurement of the test voltage
17. Test procedures
17.1 Withstand voltage tests
17.2 Disruptive discharge voltage tests
17.3 Assured disruptive discharge voltage tests
Section 6: Tests with lightning impulse voltage
18. Definitions for lightning impulse tests
18.1 Definitions of general applicability
18.2 Definitions applicable only to chopped impulses
18.3 Voltage/time curves
19. Test voltage
19.1 Standard lightning impulse
19.2 Tolerances
19.3 Standard chopped lightning impulse
19.4 Special lightning impulses
19.5 Generation of the test voltage
19.6 Measurement of the test voltage and determination
      of impulse shape
19.7 Measurement of current during tests with impulse
      voltages
20. Test procedures
20.1 Withstand voltage tests
20.2 Procedures for assured discharge voltage tests
Section 7: Tests with switching impulses
21. Definitions for switching impulse tests
21.1 Switching impulse
21.2 Value of the test voltage
21.3 Time to peak Tp
21.4 Time to half-value T2
21.5 Time above 90% Td
21.6 Time to zero To
21.7 Time to chopping Tc
21.8 Linearly rising impulse
22. Test voltage
22.1 Standard switching impulse
22.2 Tolerances
22.3 Special switching impulses
22.4 Generation of the test voltage
22.5 Measurement of test voltage and determination of
      impulse shape
23. Test procedures
Section 8: Tests with impulse current
24. Definitions for impulse current tests
24.1 Impulse current
24.2 Value of the test current
24.3 Front time T1
24.4 Virtual origin O1
24.5 Time to half-value T2
24.6 Duration of peak of a rectangular impulse
      current Td
24.7 Total duration of a rectangular impulse current Tt
25. Test current
25.1 Standard impulse currents
25.2 Tolerances
25.3 Measurement of the test current
25.4 Measurement of voltage during tests with impulse
      current
Section 9: Combined and composite tests
26. Combined voltage tests
26.1 Value of the test voltage U
26.2 Time delay triangle t
26.3 Actual voltage shapes
26.4 Arrangement of the test object
26.5 Atmospheric correction factors
27. Composite tests
Appendix A: Statistical treatment of test results
A.1 Classification of tests
A.1.1 Class 1: Multiple-level tests
A.1.2 Class 2: Up-and-down tests
A.1.3 Class 3: Successive discharge tests
A.2 Statistical behaviour of disruptive discharge
A.2.1 Confidence limits and statistical error
A.3 Analysis of test results
A.3.1 Treatment of results from Class 1 tests
A.3.2 Treatment of results from Class 2 tests
A.3.3.Treatment of results from Class 3 tests
A.4 Application of likelihood methods
A.4.1 The likelihood function
A.4.2 Estimation of U50 and z
Appendix B: Pollution test procedures
B.1 Production of salt fog
B.1.1 Preparation of salt solution
B.1.2 Details of spraying system
B.2 Pre-deposition of pollution, coating and wetting
      procedure
B.2.1 Preparation of coating material
B.2.2 Main characteristics of the inert materials
B.2.3 Solid coating and wetting procedure
B.3 Measurement of the degree of pollution
B.3.1 Surface conductivity of the insulating surface
B.3.2 Equivalent amount of sodium chloride per square
      centimetre of the insulating surface (S.D.D. mg/
      cm squared)
Appendix C: Calibration of a non-approved measurement
device with a rod/rod gap
C.1 General arrangement of a rod/rod gap
C.2 Reference values
C.3 Calibration procedure
Figures

Defines test requirements for dielectric tests with direct voltages, alternating voltages and impulse voltages and tests with impulse current. Applicable only to tests on equipment having its highest voltage greater than 1 kV. It is not intended to be used for electromagnetic compatibility tests on electric or electronic equipment.