The existence of fault resistance may add an additional reactive or capacitive component to the measured impedance seen by the protection. This may cause conventional quadrangular distance protection to overreach or under-reach under different system conditions. It is shown that the measured impedance locus with fault resistance seen by the protection is an arc that can be estimated by using voltages and currents measured by the protection. A novel adaptive algorithm for digital distance protection based on real-time measured impedance locus estimation is put forward. Theoretical analysis and digital simulation show that the new adaptive distance relay with enhanced resistive tolerance can overcome steady-state overreach for both phase to phase and phase to ground fault.