BS 7452:1991

Committees responsible
National foreword
General plan of the standard
Chapter I: General requirements
1. Scope and object
2. Definitions
3. General requirements
4. General notes on tests
5. Rating
6. Classification
7. Marking
8. Protection against electric shock
9. Change of input voltage setting
10. Output voltage and output current under load
11. No-load output voltage
12. Short-circuit voltage
13. Heating
14. Short-circuit and overload protection
15. Mechanical strength
16. Protection against harmful ingress of water and
     moisture
17. Insulation resistance and electric strength
18. Construction
19. Components
20. Internal wiring
21. Supply connection and external flexible cables and
     cords
22. Terminals for external conductors
23. Provision for protective earthing
24. Screws and connections
25. Creepage distances and clearances
26. Resistance to heat, abnormal heat, fire and
     tracking
27. Resistance to rusting
Appendix I-A Production tests
Appendix I-B Void
Appendix I-C Examples of points of application of test
              voltages
Appendix I-D Measurement of creepage distances and
              clearances
Appendix I-E Examples of points of measurement of
              creepage distances and clearances
Chapter II: Particular requirements for special
separating transformers
Section 1. Control transformers
1. Scope and object
2. Definitions
7. Marking
9. Change of input voltage setting
10. Output voltage and output current under load
11. No-load output voltage
13. Heating
17. Insulation resistance and electric strength
25. Creepage distances and clearances
Section 2. Ignition transformers for gas and oil burners
1. Scope and object
2. Definitions
4. General notes on tests
5. Rating
6. Classification
7. Marking
8. Protection against electric shock
10. Output voltage and output current under load
11. No-load output voltage
13. Heating
14. Short-circuit and overload protection
16. Protection against harmful ingress of water and
     moisture
17. Insulation resistance and electric strength
18. Construction
25. Creepage distances and clearances
Appendix II-A Void
Appendix II-B Measurement of leakage current for
ignition transformers for gas and oil burners
Section 3. High insulation level transformers and
separating transformers with working voltage above 1000V
1. Scope and object
2. Definitions
7. Marking
10. Output voltage and output current under load
11. No-load output voltage
17. Insulation resistance and electric strength
25. Creepage distances and clearances
Section 4. Stray field transformers
Under consideration
Section 5. Stabilizing transformers (current and voltage
types)
Under consideration
Chapter III: Particular requirements for auto-
transformers
1. Scope and object
2. Definitions
5. Rating
7. Marking
8. Protection against electric shock
10. Output voltage and output current under load
17. Insulation resistance and electrical strength
25. Creepage and clearance distances
26. Resistance to heat, abnormal heat, fire and
     tracking
Appendix III-A Production tests
Chapter IV: Supplementary specifications for variable
transformers
1. Scope and object
2. Definitions
6. Classification
7. Marking
8. Protection against electric shock
10. Output voltage and output current under load
11. No-load output voltage
13. Heating
15. Mechanical strength
18. Construction
21. Supply connection and external flexible cables and
     cords
25. Creepage distances and clearances
Appendix IV-A Tests during production
Chapter V: Supplementary particular requirements for
reactors
Under consideration
Figures

Single-phase or polyphase air-cooled separating transformers, auto-transformers, variable transformers and small reactors having a supply voltage not exceeding 1000 V a.c. and rated frequency not exceeding 500 Hz.