Calculations of Short-Circuit Currents in DC Systems
The calculations of short-circuit currents in dc systems are essential for the design and application of distribution and protective apparatuses used in these systems. Maximum short-circuit currents should be considered for selecting the rating of electrical equipment like cables, buses, and their supports. The simplified procedures for dc short-circuit current calculation are documented in some publications. The time variation of the characteristics of major sources of dc short-circuit current from initiation to steady state is discussed and appropriate estimation curves and procedures are outlined. A dynamic simulation is an option, however, akin to short-circuit current calculations in ac systems; the simplified methods are easy to use and apply, though these should be verified rigorously by an actual simulation. The inductances and resistances of the system components are calculated and separate resistance and inductance networks are constructed, much akin to the American National Standards Institute/IEEE method for short-circuit current calculations in ac systems.