5-262 F60 Feeder Protection System GE Multilin5.7 CONTROL ELEMENTS 5 SETTINGS5• HI-Z LOSS OF LOAD THRESHOLD: Establishes the loss of load level used as an indication of a downed conductor. ALoss of Load flag is set if the Hi-Z algorithms detect a percentage drop in phase current between two successive two-cycle RMS values that equals or exceeds the Loss of Load Threshold. The amount the phase current must decreasebetween successive two-cycle RMS values is based on this setting times the recent average phase current level. Therange is 5 to 100%; 5% being the most sensitive.• HI-Z 3-PHASE EVENT THRESHOLD: Establishes the level at which the Hi-Z element characterizes a sudden three-phase current increase as a three-phase event. The Hi-Z detection algorithms ignore the data generated by a largethree-phase event. The recommended setting is 25 A (primary).• HI-Z VOLTAGE SUPV THRESHOLD: In the event that a fault simultaneously occurs on two adjacent feeders (line volt-age from the same bus), the drop in line voltage will cause a subsequent drop in load current. This function will blockthe Loss of Load flag from being set while the voltage is depressed. Thus, if the voltage level drops by a percentagegreater than this threshold in successive two-cycle RMS samples, the Loss of Load flag will be blocked. If the setting is“0”, the voltage supervision function will be disabled.• HI-Z VOLTAGE SUPV DELAY: This setting adds time delay to the voltage supervision function. Specifically, the Lossof Load flag will continue to be blocked for the number of cycles specified by this setting.• HI-Z EVEN HARMONIC RESTRAINT: This setting determines the level of the even harmonic at which the setting ofthe overcurrent flags is inhibited. The even harmonic content is evaluated on each phase current as a percentage ofthat phase's RMS current. The intent is to inhibit the setting of the overcurrent flags if the overcurrent is simply a surgecaused by cold-load pickup or other inrush event.IMPORTANT NOTE REGARDING INSTALLATION: The F60 Hi-Z algorithm is adaptive in nature. The algorithm’sinternal thresholds gradually adapt to background “noise” on circuits with a moderate to high level of transient activ-ity. For the first three to five days after installation (or after being out-of-service for a significant period), the F60 mayidentify some of this noise as arcing. This should be taken into account when responding to alarms during thesetype of operating periods.NOTE
