A short circuit condition is an unintentional or intentional contact between two points in an electric circuit that reduces the resistance between these points that causes heavy energy flow between these points. Short Circuit Fault analysis or short circuit Fault study using ETAP is carried to determine the maximum short circuit currents, voltage and other parameters at various points in the system. Using ETAP Study tools different types of faults can be simulated and also different points in the network can be made into faulty to analyse the maximum short circuit currents at various points.

Short circuit fault study was carried out as per IEC 60909 and IEEE 399-1997 which specifies calculation of short circuit currents in three phase systems and radial systems. The anticipated maximum and minimum values of the following short circuit fault currents were calculated using ETAP 20.0 software.

• 3 phase fault kA (3 Φ)
• Line to Ground fault kA (L-G)
• Line to Line fault kA (L-L)
• Double line to ground fault kA (L-L-G)

Short Circuit (SC) fault current study as per IEC 60909 in used to order to arrive at the prospective maximum & minimum short circuit fault kA values at network components and to ensure the adequacy of various switchgear and network components, along with protective device evaluation.

The following short circuit fault study parameters were calculated: :

• Initial symmetrical short-circuit current - I"k
• Peak short-circuit current - Ip
• Symmetrical short-circuit breaking current - Ib
• Steady-State short-circuit current – Ik

The goal of short circuit study is to determine the maximum and minimum short circuit currents at different points within the network due to various faults. The Short circuit study results are very much essential for designing and selecting the short circuit ratings of the breakers and network components. The magnitude of short circuit current arrived during the short circuit study can be compared against the interruption rating of the circuit breakers and withstand ratings of switchgear components for design verification.

Minimum short circuit fault study results are significant in arriving at the settings of protection devices. By suitably selecting the protection devices and network components, the reliability of the system can be greatly improved.