Transmission & Distribution Technology
the recloser to clear the fault. If the fault is transient, then the recloser will clear the fault. However in doing so it will give all customers downstream of the recloser a momentary outage, not just those on the faulted spur line. If the fault is permanent, the sectionaliser monitors the fault current and reclose sequence and opens during the dead time of one of the reclose operations according to the configuration set.
fault, leaving all customers of the feeder affected by this spur line fault. As the recloser protection settings must take account of the load currents generated from all downstream customers, the pick-up current can be much higher than is ideal for spur line protection where the fault has actually occurred. Tis means that low level faults at the end of a spur line may not trigger the recloser protection at all. Tis can result in serious safety events such as pole top fires or downed conductors that are still energized. A sectionaliser that has operated provides line crews with a visible break at the site of the operation, but without fault interrupting capability, offers no rapid or sensitive fault protection to line crews.
Fig. 2. Performance with Fusesaver in case of permanent faults. When the Fusesaver closes, the fault is still present, resulting in an immediate fault current. The Fusesaver will not operate again and allow the fault current to blow the fuse.
Essentially, the feeder line recloser is used to clear transient faults and the sectionaliser is used to isolate a permanently faulted spur line. Unfortunately, the majority of spur line faults are transient. In case the sectionaliser fails to open in the pre-determined dead- time the recloser will have to clear the permanent
Intelligent network Furthermore, the sectionaliser has no internal fault memory capable of maintaining a record of outage events. No event log or line history exists to assist the network operator to understand the reason for the outage, nor maintain an accurate record of the length of the outage for performance reporting purposes. It cannot be integrated into a network’s SCADA system, has no capacity for remote control and does not enable operators the transition to an intelligent network. Te purchase price of the sectionaliser is relatively low, and the device itself is simple to install and replace. Single-phase reclosers may be used in place of the spur line fuse. When a fault occurs, it interrupts the fault current and recloses within a pre-determined
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