Load Flow Study and Short Circuit Study

Before creation of an Electrical Single Line Diagram for a large electrical network, it is necessary to determine the current ratings of all components of the electrical network, such as circuit breakers, disconnects, current and potential transformers, cables, transformers, capacitors, conductors etc. In addition, due to the probability of a fault in an electrical circuit (short circuit or earth fault), it is necessary to assign a short time withstand current (which is much higher than the rated current) and duration of the short time current so that frequent failure of the components do not take place due to faults. 

One commonly used tool to determine the rated normal current and short circuit current withstand of the electrical components is 'Load flow and Short circuit study' by ETAP or equivalent transient analyser software programs. It is a simulation software in which a model of the electrical network is formed in the form of a Single line diagram. The parameters of various equipment and rated load are entered into the software and then it is allowed run the calculations by Newton Raphson method or by finite element method to produce results. The results show the desired rating of various equipment in the circuit and, also, it shows the short circuit fault levels at different HV/MV/LV buses.