(2:35 p.m.) Power outage caused by Ft. Assinniboine substation

The power outage that took out the power across the Hi-Line from Chester to Glasgow was caused by a problem in the Fort Assinniboine substation.

NorthWestern Energy spokesperson Claudia Rapkoch said the outage was caused by a security measure that shuts the system down if it detects a problem. The safety feature detected a problem in one of the lines to the Fort Assinniboine substation and kicked in.

“When that system senses a problem, for whatever reason, it will isolate the problem by essentially shutting itself off,” Rapkoch said.

This safety measure is to allow operators to come in and make repairs to bring the system back up.

NorthWestern Energy received report of the outage at a quarter to noon and had everyone back in service a half an hour later, Rapkoch said.