Publications

Catching Falling Conductors in Midair—Detecting and Tripping Broken Distribution Circuit Conductors at Protection Speeds

William O’Brien
San Diego Gas & Electric Company

Eric Udren
Quanta Technology, LLC

Kamal Garg, Dennis Haes, and Bala Sridharan
Schweitzer Engineering Laboratories, Inc.

Abstract

When an overhead electric power distribution circuit conductor breaks—for example, when a car strikes a pole or a splice or clamp fails—the energized conductor falls to ground. The resulting high-impedance ground fault may be difficult or impossible to detect by relays located in the substation. In any case, no ground fault protection relay can operate until well after the time the fault has occurred—after the falling energized conductor has hit the ground and created a hazardous situation. For decades, utilities and equipment manufacturers have worked to develop methods for tripping these hazardous ground faults as quickly as possible. This paper describes a new falling conductor detection scheme that trips the affected circuit section in the narrow time window between the moment of the break and the time the conductor hits the ground. The affected circuit section is de-energized while the conductor is still falling, eliminating the risk of an arcing ground fault or energized circuits on the ground.

Wildfire Mitigation: Detecting and Isolating Falling Conductors in Midair Using 900 MHz Private LTE at Protection Speeds

Jim Li
Anterix, Inc.

Henry Loehner and Tanushri Doshi
Schweitzer Engineering Laboratories, Inc.

Abstract

The falling conductor protection (FCP) application developed by Schweitzer Engineering Laboratories, Inc. (SEL) depends upon reliable, low-latency broadband communications to de-energize broken distribution power lines as they fall, eliminating the risk of wildfire caused by arcing of live wires on the ground. This paper describes the test bed operation of the FCP application enabled by a private Long-Term Evolution (LTE) network using Anterix’s 900 MHz band spectrum. It reports that, 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. This is less than the time it takes for a broken conductor to fall to the ground, typically a distance of 25 feet.

Contact SEL Engineering Services for more information about this falling conductor mitigation solution.