In cable lines, there are problems of ensuring the effective operation of earth faults distance protection (DP) through the transient resistance due to the relatively small values of the specific parameters of the cable and the difference in the characteristics of the active and reactive resistances of the positive and zero sequences. The paper presents the efficiency estimations of distance measuring units (DMU) different algorithms operation in cables lines during the earth faults through transient resistance and analysis the impact of different zero sequence currents compensation coefficients to calculate the impedance to the fault location. To improve the efficiency of the DMU operation in the high-voltage cable line, it is proposed to synthesize an algorithm for measuring the line impedance to the fault location on the basis of a refined emergency mode model and use search optimization methods. The results of the analysis showed that the efficiency of such an algorithm is higher than the classical one and less depends on the value of the transient resistance in the fault location.