SUNDRE – A little critter that met an electrifyingly untimely end caused a brief power outage for nearly 1,000 customers.
On Thursday, Dec. 8 at 1:36 p.m. a breaker was tripped off by a squirrel, said Tanya Croft, a FortisAlberta spokesperson.
Croft told the Albertan by email in response to follow-up questions that 996 customers were affected, and that power had largely been restored by 2:02 p.m.
Only 11 customers remained without power for an additional roughly 15 minutes while the damaged switch was repaired, she said.
“Squirrels establish and follow elaborate overhead routes through their territory that often include utility poles and substations,” reads a portion of a statement provided.
“Once squirrels have established these routes, virtually nothing will force them to change, and they are not deterred by any physical barrier in their path. Because their teeth grow continuously at a rate of about 6 to 10 inches a year (15 to 25 cms), these squirrels must gnaw and chew, and they often do so on conductors and aluminum connectors on transformers.”
Of course along with squirrels and other small animals come birds of prey such as hawks, owls and eagles that can end up perching atop utility poles and roost in large groups, potentially posing a problem if they’ve chosen to nest on a distribution structure.
“In addition to outages caused by bird contacts, the birds’ droppings foul the equipment – sometimes causing arcing and outages – and create health hazards for utility employees.”
When an animal makes a contact with electrical equipment that causes a short, the temporary disturbance on the line causes a momentary outage known as a “blink.”
Blinks are an indicator that the system is functioning properly. A device called an oil circuit recloser (OCR) acts as a breaker and opens to stop the fault before quickly closing back in.
If the line is cleared of the disturbance, such as the animal falling away, the blinks cease. However, if the interruption on the line persists, the recloser will trip two more times before remaining open, resulting in a power outage.
“The OCR is an important safety mechanism that protects the system and the electrical equipment hooked up to the line. It cuts off power to the affected section of the line, isolating the problem until it can be repaired. Otherwise, the outage would affect everyone on that particular feeder.”
There was a total of 2,313 outages caused by animals, including birds, on the Fortis system from Jan. 1 to Nov. 30 of this year.
In an effort to mitigate these kinds of unfortunate encounters with wildlife and thereby reduce such outages, FortisAlberta takes preventative measures on its active overhead transformers.
“Our right-of-way maintenance program plays an important role in helping reduce animal-related outages. Since squirrels are reluctant to cross open ground, poles that are well away from trees are not as appealing to them.”
FortisAlberta works across diverse terrain that includes environmentally sensitive areas such as National as well as Provincial Parks that are home to at-risk habitats, and aims to protect natural spaces and wildlife along its power lines when completing any activities.
