This paper presents an analysis of short circuit signals by discrete wavelet transform. The signals are obtained by simulation on two four-pole UHV transmission line’s model. Both efficacy of short circuit detection and sensibility to other system’s faults are discussed. An important part of the article is to consider the great influence of well adjusted wavelet function and decomposition level on correctness and speed of short circuit detection. The adequate selection of detection algorism’s parameters based on database including the signal’s samples shows a possibility of practical use of this kind of information in real transmission lines.