Anterix, Schweitzer Engineering Laboratories release fire-mitigation test results for utilities

Anterix and Schweitzer Engineering Laboratories (SEL) announced that test results indicate that deploying low-latency private LTE networking in concert with existing utility technologies can eliminate the risk of a major cause of wildfires—live power lines as they fall to the ground.

Schweitzer Engineering Laboratories has developed a falling conductor protection (FCP) application that is designed to detect a broken distribution power line and allow a utility to de-energize the line automatically, according to a white paper jointly published by Anterix and SEL. But this functionality alone did not eliminate the fire risk, as the method of communicating the existing broken line and executing the power shutoff could take minutes, with a very real risk of a fire igniting during the interim.

But combining the SEL solution with a private LTE network operating on the 900 MHz spectrum licensed to Anterix offers significantly different results, according to the white paper.

“In a range of network congestion and signal strength scenarios, the 900 MHz private LTE network successfully supports the FCP application to de-energize the affected circuit section within one second,” the white paper states. “This is less than the time it takes for a broken conductor to fall to the ground, typically a distance of 25 feet.”

Ryan Bradetich, Schweitzer Engineering Laboratories’ senior vice president of research and development, said it takes about 1.25 seconds for a broken power line to fall to the ground, creating a fire and safety hazard. Determining whether the SEL-Anterix solution could meet this challenging threshold was the primary purpose of establishing the test bed.

“We had a lot of the equipment that we could use to detect these falling conductors, but we needed a reliable way to communicate that … to our other devices,” Bradetich said during an interview with IWCE’s Urgent Communications. “We wanted to know, ‘Can we detect that falling conductor before it hits the ground?’ We know that we have about 1.25 seconds to open that circuit breaker to interrupt the [electrical] current, so it wouldn’t arc when it hits the ground. What we showed through our testing is that we can do it in plenty of time.

“What’s nice about this wildfire application is that … we’re not introducing anything new—they can use the protocols that are already in the relay. It’s the algorithm and the network that makes it fast enough to solve a new problem, which is that wildfire mitigation.”

Anterix COO Ryan Gerbrandt echoed this sentiment, noting that this has been one of the most “challenging” safety issues faced by utilities, particularly in recent years.

“One of the reasons we wanted to do this work was to validate the use case and make sure that it’s proven,” Gerbrandt said during an interview with IWCE’s Urgent Communications. “We understand some of the details round the operating condition, which was one of the purposes of the testing—not just to test the use case under ideal circumstances but try to bring some real-worldism into the use-case testing, so that we feel confident that it’s going to be scalable and portable as we bring it out to the field.

“Historically, this type of fault is not one that’s readily picked up by the current fault relay systems,” Gerbrandt said during an interview with IWCE’s Urgent Communications. “[Utilities have had] a way to implement this, but … the key missing piece has been the telecom network that could support the required inter-device communication and the command-side activities at a low enough latency to actually have a meaningful outcome.”

Indeed, the implications of the Anterix-SEL solution could have significant impacts to utilities and the customers they serve.

Utilities have been required to pay tens of billions of dollars—driving one utility, PG&E, into bankruptcy—after being deemed responsible for starting or contributing to dozens of wildfires that have led to more than 100 deaths and burned millions of acres, including the Camp Fire that destroyed the town of Paradise, Calif.

In an effort to mitigate such a fire risk, some utilities have utilized the strategy of public safety power shutoffs, turning off electricity service to a geographic area to eliminate the possibility of downed power lines starting fires in high-wind environments. This practice was used extensively in California during the fall of 2019, when it was criticized heavily by consumers and state officials.

If the Anterix-SEL solution works, the risk of fire from downed power lines and the need for public safety power shutoff should be reduced significantly. This also could impact utilities’ long-term insurance liability, according to sources familiar with the situation.

But Gerbrandt noted that there are other scenarios for utilities contributing to wildfires, noting that “there is no silver bullet” to resolve the issue.

“This is certainly a tool, or an arrow in the quiver” as utilities try to make their critical infrastructure safer, Gerbrandt said.

San Diego Gas & Electric (SDG&E) cited this wildfire-mitigation capability as a key reason why it signed a $50 million deal with Anterix in February 2021. Gerbrandt said that SDG&E tested this functionality for the utility’s purposes prior to signing the agreement, but the recent Anterix-SEL testing was able to examine various use cases more comprehensively.

Among the different scenarios examined was whether the private LTE (PLTE) network would perform well enough to meet the wildfire-mitigation solutions needs, even if the signal strength was low.

“This experiment demonstrates the function of FCP and its latency performance over PLTE under different congestion and signal scenarios,” according to the white paper. “Prioritization allows for reliability of application traffic. Based on the above results, we recommend operating FCP traffic over higher-priority service.

“With high, medium, and low LTE signal strength and quality, FCP also performs within protection limits. It is notable that the function of FCP still performs within the limits of the application metric, even under lower signal condition. This indicates the robust design of LTE to achieve low latency.”