Detecting and Managing Energized Downed Conductors

Detecting energized downed conductors in utility distribution systems remains an challenge problem. When there is downed energized conductor, in many cases, the electric utility is not aware of the issue until it is reported. Meanwhile these downed energized conductor poses serious safety hazard causing electrocution when contact with humans or in some cases can result in an wildfire. The challenge in detecting energized downed conductors lies in the fact that when a wire is down, it does not draw much current creating a high impedance fault which usually does not trigger imbedded protection systems. Storms and car accidents are common causes of downed wires as shown in image below.

Image Credit:Downed Wire Safety (Unitil)

The amount of current drawn in a downed conductor depends on the soil type. Grounded downed conductors typically carry 10-20A, which is below the typical fuse rating of 80A, preventing the fuse from being activated. Normal relays are not effective in detecting such low impedance faults.

The existing prevent use of single phase reclosers also add to this issue, because the recloser, only sees a fault, but will now know that the conductor has broken and thereby the recloser will continue activate  to try to clear the circuit and continue to energize the line. 

There are new technologies that are being developed to address this issue. Advanced relays, AMI meters, and algorithms that analyze current signatures are being currently being explored. One such algorithm called "arc sense" examines cycle-to-cycle variations to detect these impedance faults.

Other technologies that work with Advanced Metering Infrastructure (AMI) can help identify voltage losses, which are then reported to the recloser through an Outage Management System (OMS). In cases where SCADA indicates the recloser is closed but the OMS reports an outage, it indicates a live downed wire.

To effectively track downed conductors, utilities require AMI, outage visualization, and SCADA on the distribution system. However, not all devices provide outage notifications, and many utilities struggle to accurately track the number of downed conductors. For most utilities, it is challenging to track downed conductors. In most case, the utilities don’t have a special code restoration code to track downed conductors.

To address these challenges, it is crucial to track downed conductors, understand their location and cause, and implement detection technologies. Overall, detecting and managing energized downed conductors requires a combination of technological advancements, regulatory attention, and proactive measures to ensure the safety and reliability of utility distribution systems.