This paper presents a new fault location algorithm for three-terminal transmission lines, with the help of synchrophasor data. The algorithm utilizes the information of voltages and currents which are available from all the three ends. The proposed algorithm utilizes positive and negative sequence data for locating asymmetrical faults and only positive sequence data for locating symmetrical faults. The accuracy of the algorithm has been evaluated for various factors, such as fault inception angles, fault resistance, fault location, synchronization errors, measurement errors. The simulation of faults on the system have been carried out using PSCAD® and the algorithm is implemented in MATLAB software. Based on the simulation results it has been observed that the % error is less than 1.5% for 178 test cases out of 180, which shows 98.8% accuracy. © 2020 Elsevier B.V.