The effects of fault clearance practices on adjustable speed drives

Rapid three-phase “fuse saving” fault clearance practice has been widely used in power systems. However, most of the faults on power systems are single-line-to-ground (SLG) faults. Under this condition, single-phase tripping with automatic reclosure can be an attractive alternative because it only introduces short term disruption of power supply to the faulted phase. It has not been widely used in distribution systems because of the consideration that it could lead to some imbalance to three-phase loads such as adjustable speed drives (ASD). The study compares the effects of three-phase tripping with that of single-phase tripping on ASD. It is shown that single-phase tripping improves the quality of power supply. Also, the degree of imbalance during fault clearance is considered acceptable