BS 7638:1993

Committees responsible
National foreword
Foreword
1 Scope
2 Object
3 General calculation methods and calculation
      assumptions
4 Definitions
4.1 Short circuit
4.2 Far-from-generator short circuit
4.3 Short-circuit current
4.4 Prospective (available) short-circuit current
4.5 Initial symmetrical short-circuit current Ik"
4.6 Peak short-circuit current ip
4.7 Symmetrical short-circuit breaking current ib
4.8 Steady-state short-circuit current Ik
4.9 Nominal system voltage Un
4.10 Short-circuit impedances of electrical equipment
4.11 Short-circuit impedances at the short-circuit
      location
4.12 Voltage source
4.13 Equivalent voltage source cUn/square root of 3
4.14 Voltage factor c
5 Symbols, subscripts and superscripts
5.1 Symbols
5.2 Subscripts
5.3 Superscripts
6 Short-circuit types
7 Calculation methods and assumptions
7.1 Symmetrical components
7.2 Equivalent voltage source at short-circuit
      location
7.3 Conditions for disregarding the influence of
      motors
8 Short-circuit impedances of electrical equipment
8.1 High-voltage network feeders
8.2 Transformers
8.3 Overhead lines and cables
8.4 Other impedance elements
8.5 Conversion of impedances
9 Calculation of short-circuit currents
9.1 Balanced three-phase short-circuit current
9.2 Line-to-line short-circuit current without earth
      connection
9.3 Line-to-earth short-circuit current
10 Example of short-circuit current calculations
      using forms
10.1 General procedure
10.2 Explanations for using the calculation forms
11 Example for a housing installation
11.1 Network diagram
11.2 Data of electrical equipment
11.3 Special remarks
Forms
Annex
ZA (normative) Other international publications
      quoted in this standard with the references of the
      relevant European publications
National annex
NA (informative) Cross-references

Specifies a standardized procedure developed from BS 7639 for calculation in three-phase a.c. systems operating at 50Hz or 60Hz