This paper proposes a fast fault classification technique using three phase current signals for power systems. Digital Fourier Transform, the ‘Least Square’ method or the Kalman Filtering technique are used to extract fundamental frequency components of three phase fault currents. Fast fault classification can be achieved using the fault probability of three phases. Results from simulation work on EMTP have validated the proposed fault classification technique. The response time of the fault classification technique using the ‘Least Squares’ method is 1.875ms (3 samples) for single-phase-to-earth fault, two-phase-to-earth fault, two-phase-fault and three-phase fault.