Abstract
This paper presents an algorithm to provide current based scheme for protection of transmission line. The proposed algorithm is implemented using harmonic wavelet transform (HWT) and rule based decision tree. Current measured on two ends of transmission line has been decomposed using harmonic wavelet transform. Absolute values of output of harmonic wavelet transform based decomposition of current signal is taken as fault index and plotted for recognition of faults. Peak values of the fault indexes are used as input data to rule based decision tree to classify faults. Proposed current based scheme proved to be effective in detection and classification of transmission line faults to provide efficient protection to line.