For the safety of our community, customers and our forests, Nelson Hydro has turned off the automatic reclosers on our distribution lines as a wildfire safety measure.
Automatic reclosers can quickly restore power after outages, but they can also multiply the fire risk from damaged lines as they produce sparks by design. During times when the fire danger rating is high to extreme, the reclose setting is turned off to avoid the potential of starting interface fires.
This results in more frequent and longer outages since, without the reclosers, crews need to respond to patrol the lines and manually restore power once the issue has been identified.
In electric power distribution, automatic circuit reclosers (ACRs) are a class of switchgear that is designed for use on overhead electricity distribution networks to detect and interrupt momentary faults. Also known as reclosers or auto reclosers, ACRs are essentially high voltage rated circuit breakers with integrated current and voltage sensors and a protection relay, optimized for use as an overhead network distribution protection asset.
For overhead distribution networks, the majority of faults are transient, such as lightning strikes, surges or foreign objects (branches, birds) coming into contact with the exposed distribution lines. By this logic, 80% of outages can be resolved by a simple re-close operation as they make quick work of many line faults.
The recloser detects a power surge, momentarily interrupts electricity flow, and then automatically recloses its contacts to restart flow down the affected line.
Reclosers usually try restarting a line two to three times before giving up and “locking out” a line. Sometimes multiple attempts are needed to do the job, such as when high-temperature electrical arcing at the site of the fault burns away hung trees or tree limbs.
Under the wrong conditions, such arcing and ignition can obviously spark a fire.
We thank you for your understanding as we strive to keep everyone safe this summer.
In photo: The rectangular boxes are the reclosers.