February 13, 2020
Ergon Energy has begun helicopter patrols in the Blackbutt / Benarkin area to check poles and wires after a string of recent blackouts in the region.
Since the beginning of December there have been 17 unplanned power outages and one forced power outage on a long rural feeder line which supplies properties in the area.
Ergon Energy responded to complaints by a local resident with an emailed apology but noted the feeder line posed “a number of challenges given its length and high exposure to the elements”.
The lengths of the blackouts ranged from momentary outages that lasted less than a minute to almost 16 hours.
The longest blackout was caused by a conductor which came down during storms.
Other power outages were caused by a tree falling on a line and a broken cross-arm.
One blackout, on December 6, occurred after heavy demand during hot weather tripped protection equipment; this was linked to a temporary repair four days earlier.
Protection equipment also cut in on several occasions after external impacts to the line, eg. from vegetation, wildlife or lightning strikes.
This “auto recloser” equipment is designed to turn the power off momentarily, wait for a predetermined time (about four seconds) and then try to turn the power back on.
If the fault is still present, the recloser turns the power off and on again. If it decides the fault is permanent, it shuts off the power until crews can attend, locate the fault and restore supply.
“If there were no auto-reclose devices on the line then the whole line would ‘trip’ every time there is a transient fault (eg. lightning strike) and repair crews would have to investigate the whole line, sometimes hundreds of kilometres, to locate the fault, not just the smaller portion isolated by the auto recloser,” the Ergon spokesperson said,
“Therefore auto reclosers are effective and necessary to prevent damage to the powerline and locate faulted sections quickly, reducing restoration times.
“Unfortunately, a by-product of this protection system is momentary outages. In the wet season, an intermittent fault can develop due to passing rain showers which causes the auto recloser to operate multiple times. This type of fault is very difficult to locate, hence the constant tripping until someone sees a flash and reports it, or the fault becomes permanent and traceable.”
The spokesperson said the feeder line was last inspected in March 2017 and no serious defects that required urgent attention were identified.
It was next due to be inspected in 2022 however Ergon is now “fast-tracking” several projects to address the reliability issues.
“Ergon Energy is attempting to fast track a project to install two additional auto-reclosers on to the feeder and anticipate this will be completed in the near future,” the spokesperson said.
“This project will enable us to locate and isolate the fault sooner and potentially lessen the impacted areas, in addition to reducing the duration of the outage event, resulting in improved restoration and response times to any localised problems.”
- Related article: Fallen Trees Caused Blackouts
