IMPORTANCE SHORT CIRCUIT (OR) FOR FAULT ANALYSIS
A fault in a circuit is any failure which interferes with the normal flow of current. The faults are associated with abnormal change in current, voltage and frequency of the power system.
The faults occur in a power system due to
(i). Insulation failure of equipment
(ii). Flashover of lines initiated by a lighting stroke
(iii). Due to permanent damage to conductors and towers or due to accidental faulty operations.
(i) Series fault or open circuit fault
One open conductor fault
Two open conductor fault
(ii) Shunt fault or short circuit fault. Symmetrical fault or balanced fault
§ Three phase fault
Unsymmetrical fault or unbalanced fault
§ Line to ground (L-G) fault
§ Line to Line (L-L) fault
§ Double line to ground (L-L-G) fault
This type of fault is defined as the simultaneous short circuit across all the three phases. It occurs infrequently, but it is the most severe type of fault encountered. Because the network is balanced, it is solved by per phase basis using Thevenins theorem or bus impedance matrix or KVL, KCL laws.