The effect on the generator excitation magnetic field is different when the capacity and power factor of load are different, and the effect on the internal impedance voltage drop is different, too.

At higher impedance levels, circuit settling times become more important and are usually the overriding factor in determining overall measurement speed.

Because the impedance fault location method is easily influenced by the factor such as fault resistance, transformer error and asymmetrical line configuration, the fault location accuracy is lower.