How Components Work to Reduce Outage Times and Improve Reliability
United Power’s outage restoration system is among the most advanced and innovative in the country. While the cooperative has a national reputation for its forward-thinking beneficial energy projects, behind the scenes it has also dedicated significant resources to improve system reliability and reduce member outage times. The result is one that utilizes a sophisticated network of automated field devices that allow system operators and line crews to respond and resolve outages more quickly while often also preventing larger outages affecting more members.
Automated field devices fall into a varying spectrum from simple to complex, but they all work in conjunction to identify, isolate and, when possible, resolve “faults.” A fault is when the flow of electricity is abnormal or interrupted and can be caused by any number of incidents, such as weather, vegetation or equipment failures. Automated devices detect these faults and respond to them. Each type of device has a different response but all have the same purpose – to keep your lights on.
Fuses are not automated, but they are the simplest and least expensive means of protecting the cooperative’s system from fault damage and preventing larger outages. Fuses are “sacrificial” devices used to isolate small areas. They blow quickly in response to a fault, usually resulting in a relatively small outage impacting only a handful of members while maintaining service to any remaining members downstream of the fault. Line crews are able to quickly and easily replace these devices to restore power. Think of fuses like GFCI outlets in your home. When they detect an abnormal current, they shut off power to protect you.
The next level of protection against faults are reclosers and breakers. Although reclosers and breakers are technically separate devices, they function in similar ways. They protect much larger service areas and can respond to a fault in just a few seconds. This fault response is the most common cause of power “blinks.” When your house lights dim temporarily or you lose power briefly, this is caused by a breaker detecting a fault and responding. Breakers will attempt to reclose automatically to determine if the fault is still present. In the event of a sustained fault, system operators can reclose some breakers remotely once the fault has been cleared, limiting outage times for members impacted. While fuses in your home will shut off power to a single outlet, a breaker will shut off power to entire section of your home when it detects an overloaded circuit.
Switches are another remote device United Power system operators can use to quickly restore power to members affected by an outage. They are used to reroute the distribution of power to restore members while isolating the segment of line with the fault, also known as a redundancy, or the ability to serve members from more than one substation. Before remote switches, lineworkers had to manually activate switches, which required a lot of manpower and guesswork. In most cases, rerouting power with a switcher can restore power to most members within minutes or even seconds. In a few cases, it can restore power to all members. United Power is in the process of upgrading more switches to remote field devices.
System redundancies allow United Power to serve approximately 90 percent of its members from at least two different substations or circuits. The cooperative is continually looking for solutions to construct backup facilities serving remaining members but have been limited by geographical challenges. The approach to installing automated and remote field devices is a strategic method that allows the cooperative to better serve members, resulting in fewer outages where possible, shorter outages where not and improved overall system reliability.
“What we’re doing with automated devices is well ahead of your average electric utility,” said Engineering Director Robert Maxwell. “We’ve been continually reviewing our system and its performance to identify where installing automated devices would best serve our members.”