Discussion of "Stand alone intelligent digital distance relay"

The author discusses the paper "Stand alone intelligent digital distance relay" (see ibid., vol.15, no.1, p.137-42, 2000). The proposed method is tested for single-phase to ground faults. The author question whether, if other types of faults are considered, as in the practical application, might the fault classification be needed before the impedance is measured? The original authors' responses to this discussion are also included in the paper.