scope:

This International Standard is applicable to the mechanical and thermal effects of short-circuit currents. It contains standardized procedures for the calculation of the effects of the short-circuit currents in two sections as follows:

- Section 2 - The electromagnetic effect on rigid conductors and flexible conductors.

- Section 3 - The thermal effect on bare conductors and electrical equipment.

For cables and insulated conductors reference is made, for example, to IEC 949 and IEC 986.

Only a.c. systems for rated voltages up to and including 420 kV are dealt with in this standard.

The following points should particularly be noted:

1) The calculation of short-circuit currents should be based on IEC 909.

2) Short-circuit duration used in this standard depends on the protection concept and should be considered in that sense.

3) These standardized procedures are adjusted to practical requirements and contain simplifications with safety margins. Testing or more detailed methods of calculation or both may be used.

4) In section 2 of this standard, for arrangements with rigid conductors, only the stresses caused by short-circuit currents are calculated. Furthermore, other stresses can exist, e.g. caused by dead-load, wind, ice, operating forces, earthquake. The combination of these loads with the short-circuit loading should be part of an agreement and/or be given by standards, e.g. erection-codes.

The tensile forces in arrangements with flexible conductors include the effects of dead-load. With respect to the combination of other loads the considerations given above are valid.