APTP Articles

Safe Sectionalising with Innovative & Reliable Switchgear

Traditionally, pole mounted sectionalising equipment is deployed to enhance the effectiveness of pole mounted reclosers in an overhead distribution network. Modern and innovative sectionalisers provide improved network reliability with reduced installation costs and form part of overhead network designs and assets strategies.

Sectionalising equipment operates by reliably detecting and counting upstream reclose operations. When a user-configured number of counts is reached, the sectionaliser opens during the reclose / dead time of the upstream recloser’s sequence. The successful operation of the sectionalising device contributes significantly to the success of the upstream recloser’s automatic restorations and minimises the number of customers affected. 

Reliable Operation of Sectionalising Equipment

As with line and lateral recloser operations, sectionalising equipment protection functions must always operate. For sectionalising equipment, the protection function is to detect a fault being interrupted by the upstream recloser and count them. This function should be active and ready to operate at all times, without delay or wake up time. Ideally, deployed line and lateral recloser assets can be configured to perform also as the sectionalising equipment via simple firmware or configuration changes. 

Easy and fast firmware change via ANT antenna in the depot

To reliably enhance the effectiveness of recloser operations, sectionalising equipment must be provided with a battery backup auxiliary supply, powered either by line voltage or line current. Relying solely on fault current to initiate the protection operation (i.e., to initiate the count) could lead to unexpected behaviour. For example, if the sectionalising equipment misses a downstream low level or high impedance fault, the upstream recloser may lockout unintentionally. These circumstances, if they occur, make it difficult for linespersons to find the fault and add considerable time to restore supply.

Enhancing Sectionalising Equipment Safety Through Design 

Rural and semi-rural feeders present challenges in maintaining reliability. Outages generally affect longer distances of the network in areas without communications infrastructure. Restorations often require manual operation of sectionalising equipment. Sectionalising devices with on board line fault indicators provide a clear reference to linespersons, guiding them directly to faulted regions of feeders.