IEC 60949:1988 PDF (Not Available)

IEC 60949:1988 standard provides a methodology to calculate the permissible short-circuit currents in electrical systems. The standard follows a three-step approach to determine these currents.

Firstly, it requires calculating the adiabatic short-circuit current. This current represents the maximum possible current that can flow in a short-circuit condition without considering any thermal effects.

Secondly, a modifying factor is calculated to account for the non-adiabatic heating effect. Non-adiabatic heating refers to the heat generated during a short-circuit event that is not dissipated quickly enough. This factor quantifies the impact of this heating effect on the permissible short-circuit current.

Lastly, the permissible short-circuit current is obtained by multiplying the adiabatic short-circuit current with the modifying factor. This final result represents the maximum current that can flow during a short-circuit event, taking into account both adiabatic and non-adiabatic heating effects.