Discussion of “An Evaluation of Some Alternative Methods of Power Resolution in a Large Industrial Plant”

3) the superimposed current is detected within a defined time window after fault inception. The relay will not respond to any disturbance outside this window. By this arrangement, the superimposed currents due to switching and energization generated are effectively excluded; 4) the proposed technique cannot detect the operation of the remote circuit breaker (CB) when one of the parallel lines is out of service. In this case, the “Instant” or “Delayed” operation scheme can be adopted depending on the fault types; 5) the algorithm is used in connection with the phase selection algorithm of the relay; therefore, the decision will be made after receiving information about the fault type from the phase selector. 6) the discusser clearly picks up a crucial point. Due to the mutual coupling between the two circuits, the protection algorithm will meet a problem for this extreme case of a single phase fault close to the remote busbar. In this case, the comparison of the levels of SI currents and the ratios between the two circuits is able to determine the faulted circuit; 7) the algorithm has not been tested with any evolving fault case. The authors do agree and have a plan to perform such tests; 8) simulation studies show that the technique performs reliably for most fault conditions. Initial studies also show that the disconnection of the source at busbar R has little effect on the performance.