   , Vol. 14, No. 3, pp. 207217, 2009. © Association for Scientific Research           Sava Koç*, Zafer Aydoğmu** * Department of Electrical Education, Batman University Technical Education Faculty– BATMAN ** Department of Electrical Education, Firat University Technical Education Faculty – ELAZIĞ  A MATLAB/GUI (Graphical User Interface) based simulation tool has been developed to calculate the shortcircuit fault currents in power transmission lines and to use as an educational material for courses on power system analysis. Presented program provides the calculation of threephase (3LS), single linetoground (1LG), linetoline (2LS), and double linetoground (2LG) faults on transmission lines. Symmetrical components of currents and voltages are used for calculations in the program. By means of the program, calculated fault currents and voltages on the fault point of the line have been presented both in perunit and in real values. Furthermore, this calculated currents and voltages can be observed in GUI screen. In this way, an educational tool has been developed for the students to check the accuracy of their calculations and to observe the variations of waveforms. The purpose of this GUI based tool is to help the student to understand the concept of symmetrical components and shortcircuit faults. !"# Short circuit, Symmetrical components, Graphical User Interface. $%  There are a number of different types of faults that may occur in power systems. Three phase symmetrical fault occurs in three phase systems where the phase conductors are in contact with each other. The phase to phase fault occurs when two phase conductors are in contact with each other. A single phase to ground fault occurs between a phase conductor and neutral conductor or ground conductor in three phase grounded neutral systems. If two phase conductors are in contact with the neutral or ground conductor, a two phase to ground fault occurs. Fault analysis is very important part of power system analysis. Students have difficulties to understand the concept of faults and method of calculations. Teaching symmetrical fault analysis is easier than teaching unsymmetrical faults to the students. One reason for the difficulty can be attributed to the increased numerical complexity in dealing with the symmetrical components in the unbalanced three phase environment. This complexity leads to a loss of focus and lack of understanding of the basic processes affecting the values of currents and voltages after the occurrence of a fault and the students become indifferent to the variation in the results from one type of fault to another [1].