Since 1945, electric power systems have been extremely important due to huge increase in the electric energy demand. As a result, power transmission lines have been rapidly developed in number and length. Any disturbance or the tripping of transmission line may lead to failure of supply in wide area. This requires the effective protection of these lines. The analysis of faults with different loads helps in the detection of transients which ultimately helps in the localization, detection and classification of power system faults to provide efficient protection system. This paper presents a discrete wavelet transform (DWT) based methodology for detection of transmission line faults. The investigated faults include line to ground fault, double line fault, double line to ground fault, and three phase faults. The detailed study of detection of faults has been carried out in MATLAB/Simulink environment.