Fault induced conductor motion

In utility protective relaying, faults or short-circuits on overhead distribution lines frequently cause conductor movement, which results in a subsequent fault closer to the source. Very often a backup protective device operates for these conditions leading to the suspicion that the coordination of the protective devices is improper. Under phase-to-phase faults, the more frequent situation involving this phenomenon, the conductors are forced apart by the short-circuit forces. Even though the closest protective device (recloser) operates, the conductor motion often bring the conductors together. Thus, one would get a recloser operation as well as a circuit breaker operation. In some cases, the circuit breaker locks out for this situation. As a result, a much larger area is interrupted. This paper builds upon a modeling effort to match what happens in the field and to determine what remedies have the best chance of success in dealing with fault-induced conductor motion (FICM). The authors investigated some real-world examples that occurred on the distribution system and evaluated alternatives to deal with them.