Comparison of high-speed adaptive and nonadaptive backup overcurrent protection on fuse feeders with sensors

In traditional power distribution systems, feeder fuses are coordinated with a backup relay without using adaptive protection and sensors. The backup relay is set by selecting the maximum fuse ampere rating and using the relay's resident functions. Because of this, the backup relay is set at the same inverse time-current curve for all fuses. In this study, to improve the speed and selectivity of the backup relay at busses with different fuse ampere ratings, the backup relay was set at different inverse time-current curves depending on the maximum ampere rating of the fuses they are connected to. Tests for the adaptive backup overcurrent protection showed how the backup relay selected the settings based on the connected maximum ampere rating fuse, and the relay speed increased up to 32.86%. The backup relay adaptive protection improved the selectivity and speed for clearing the faults, respect to the nonadaptive protection.