Now that Minnkota is five years into its accelerated plan to address blink outage issues on its power delivery system, the impact of the mitigation strategy is becoming clearer.
The member cooperatives and Northern Municipal Power Agency participants are seeing blink outages reduced by an average of 50% on treated lines.
“We have seen some circuits that have been reduced by as much as 75%,” said Evan Edwards, Minnkota engineer. “Circuits that are located in open prairie terrain have seen the largest positive impact so far.”
Minnkota’s open prairie line sections tend to have a higher exposure to lightning and wildlife, along with insulator contamination due to dust and blowing conditions. Technologies have been installed on structures across Minnkota’s 2,100-mile subtransmission system to address these issues. By 2020, Minnkota will have performed blink mitigation on more than 1,200 miles of those 69-kilovolt (kV) structures.
While it is virtually impossible to completely eliminate all blink outages, installing the mitigation measures has proven to be a cost-effective way for Minnkota to improve reliability and service to the membership. Structures are being fitted with a hanging lightning arrester, a polymer post-top insulator, a raptor deterrent (pole helmet) and a climbing animal deterrent (pole wrap).
“All aspects of the blink mitigation process have contributed to the positive impacts, but the most impactful changes seem to be the new post top, pole helmet and pole wrap,” Edwards said.
Minnkota crews and contractors have been working safely and efficiently as they move from pole to pole along the power delivery system. In some cases, the lines remain energized while the work is being completed so that service is not interrupted to the member-consumers. Specialized equipment is used to complete this “live line” work.
About 200 miles of lines have been treated this year. The same number of miles has been targeted for 2020, which is planned to be the final year of major blink outage mitigation efforts. The focus is beginning to shift toward a structured program to rebuild aging lines across the system.
A significant portion of Minnkota’s subtransmission system has aged beyond its 50th year of service. While progress has been made to lower blink outage exposure, expectations from consumers continue to rise. This is primarily driven by the fact that today’s electronics require a constant, uninterrupted supply of power to run properly.
In the past, a blink would occur and often go unnoticed to the average consumer because there were no digital displays that needed to be reset afterward. Today, each blink outage is documented by the flashing “12:00.”