BS 5311:1988

National foreword
Committees responsible
Chapter I: Service conditions, definitions, rating,
construction and design
1. Scope
2. Normal and special service conditions
3. Definitions
    3.101 General terms
    3.102 Switching devices
    3.103 Parts of circuit-breakers
    3.104 Operation
    3.105 Characteristic quantities of circuit-breakers
    3.106 Index of definitions
4. Rating
    4.1 Rated voltage
    4.2 Rated insulation level
    4.3 Rated frequency
    4.4 Rated normal current and temperature rise
    4.5 Rated short-time withstand current
    4.6 Rated peak withstand current
    4.7 Rated duration of short-circuit
    4.8 Rated supply voltage of closing and opening
           devices and auxiliary circuits
    4.9 Rated supply frequency of closing and opening
           devices and auxiliary circuits
    4.10 Rated pressures of compressed gas supply for
           operation and for interruption
    4.101 Rated short-circuit breaking current
    4.102 Rated transient recovery voltage for terminal
           faults
    4.103 Rated short-circuit making current
    4.104 Rated operating sequence
    4.105 Rated characteristics for short-line faults
    4.106 Rated out-of-phase breaking current
    4.107 Rated line-charging breaking current
    4.108 Rated cable-charging breaking current
    4.109 Rated single capacitor bank breaking current
    4.110 Rated back-to-back capacitor bank breaking
           current
    4.111 Rated capacitor bank inrush making current
    4.112 Rated small inductive breaking current
    4.113 Rated time quantities
    4.114 Co-ordination of rated values
5. Design and construction
    5.1 Requirements for liquids in circuit-breakers
    5.2 Requirements for gases in circuit-breakers
    5.3 Earthing of circuit-breakers
    5.4 Auxiliary equipment
    5.5 Dependent power closing
    5.6 Stored energy closing
    5.7 Operation of releases
    5.8 Low and high pressure interlocking devices
    5.9 Nameplates
    5.101 Requirements for simultaneity of poles
    5.102 General requirement for operation
    5.103 Pressure limits of compressed gas for
           interruption in gas blast circuit-breakers
    5.104 Vent outlets
Figures 1 to 14
Chapter II: Tests, selection, orders and installation
6. Type tests
    6.1 Dielectric tests
    6.2 Radio interference voltage (r.i.v.) tests
    6.3 Temperature-rise tests
    6.4 Measurement of the resistance of the main
           circuit
    6.5 Short-time withstand current and peak
           withstand current tests
    6.101 Mechanical and environmental tests
    6.102 Miscellaneous provision for making and
           breaking tests
    6.103 Test circuits for short circuit making and
           breaking tests
    6.104 Short-circuit test quantities
    6.105 Short-circuit test procedure
    6.106 Basic short-circuit test-duties
    6.107 Critical current tests
    6.108 Single-phase short-circuits tests
    6.109 Short-line fault tests
    6.110 Out-of-phase making and breaking tests
    6.111 Capacitive current switching tests
    6.112 Magnetizing and small inductive current
           switching tests
7. Routine tests
    7.1 Power frequency voltage withstand dry tests
           on the main circuit
    7.2 Voltage withstand tests on control and
           auxiliary circuits
    7.3 Measurement of the resistance of the main
           circuit
    7.101 Mechanical operating tests
    7.102 Design and visual checks
8. Guide to the selection of circuit-breakers for
    service
    8.101 General
    8.102 Selection of rated values for service
           conditions
    8.103 Selection of rated values for fault conditions
9. Information to be given with enquiries, tenders and
    orders
    9.101 Information to be given with enquiries and
           orders
    9.102 Information to be given with tenders
10. Rules for transport, storage, erection and
    maintenance
    10.1 Conditions during transport, storage and
           erection
    10.2 Erection
    10.3 Maintenance
Figures 15 to 32
Chapter III: Appendices
Appendix AA - Calculation of transient recovery voltages
              for short-line faults from rated
              characteristics
Appendix BB - Capacitor bank inrush currents
Appendix CC - Records and reports of type tests for
              making, breaking and short-time current
              performance
Appendix DD - Determination of short-circuit power factor
Appendix EE - Tightness specifications and tests
Appendix FF - Method of drawing the envelope of the
              prospective transient recovery voltage of
              a circuit and determining the
              representative parameters
Appendix GG - Methods of determining prospective
              transient recovery voltage waves
Appendix HH - Example of a commissioning test programme

Requirements for a.c. circuit-breakers (other than for electrical traction equipment and overhead lines) for indoor or outdoor installation for operation at frequencies up to 60 Hz with voltages above 1000 V. Applies only to 3-pole circuit breakers for use in three-phase systems and single-pole circuit breakers for use in single phase systems.