Self-healing Distribution Circuit Restores Power in 60 Seconds

At Distributech International this week in San Diego, S&C Electric Company launched the EdgeRestore underground distribution restoration platform for residential loops. EdgeRestore is a fully automated solution able to isolate faults in difficult-to-access, underground residential distribution circuits, allowing power to be restored to homes quickly.

The new system is easy for grid operators to install in existing residential transformers and facilitates safer repairs. EdgeRestore locates and isolates faults, reducing the occurrence of extended power outages by automatically rerouting and restoring power within 60 seconds.

 

Underground distribution circuits power many homes. Image used courtesy of S&C Electric

Residential Distribution Moves Underground

With severe weather events becoming more prevalent, utilities are proactively looking for ways to improve the reliability and resilience of their grid infrastructure. One solution is to move high-capacity, lateral electric cabling below ground, where it is less exposed to the effects of severe weather conditions like high winds, icing, or falling limbs.

But moving cables below ground presents its own set of challenges. Underground lines are still susceptible to faults as cables degrade over time. Splices and other connectors are prone to failure as they age and from repeated mechanical use.

When faults occur in underground residential distribution circuits, it almost always results in a permanent loss of power to homes, requiring multiple “truck rolls” to implement repairs. At the same time, customers wait for power to be restored.

First, an emergency crew is dispatched to locate and isolate the fault. This typically involves manually testing individual transformers within the residential distribution circuit to identify the fault location. A second crew is then assigned to come back to repair the fault, with the entire diagnosis and repair cycle taking several hours or more.

 

Emergency “truck roll” to locate and isolate a residential fault. Image used courtesy of S&C Power

 

Isolating Faults and Restoring Power with EdgeRestore

The EdgeRestore platform operates within the last mile of underground residential loop distribution circuits. It quickly locates and isolates faults or single-source power losses and re-routes power from alternate sources to residential loads, typically within 60 seconds.   

As a remote, automatic, and “self-healing” intervention, it eliminates the need for utility operators to immediately send out an emergency truck roll to locate and isolate the fault. With the fault automatically isolated and power restored, they can wait for weather, or other site conditions, to improve before sending out a repair crew.  

Also, when the repair crew arrives on scene, integrated switching within the EdgeRestore platform makes it easier for them to effect repairs while minimizing their exposure to medium-voltages and other repair hazards. 

Individual faults can be isolated by designing residential loops with multiple power sources while maintaining power to all homes. Each EdgeRestore unit uses peer-to-peer communication via the power line carrier to determine which devices should operate, isolating the circuit fault while restoring power to all loads.

 

EdgeRestore isolates faults and restores power to homes. Image used courtesy of S&C Electric

From a specification standpoint, the EdgeRestore bushing well interrupters are rated up to 15.2 kV (single phase to ground), 80 A of continuous current, and 6300 A of short-circuit current at 50/60 Hz power. 

 

EdgeRestore fault isolation and switching gear. Image used courtesy of S&C Electric

 

Reducing Outage Time While Saving Costs

Even a single fault can result in thousands of outage minutes. By restoring power to homes within 60 seconds, S&C claims that the EdgeRestore platform reduces outage time for customers and improves key customer-centric metrics for utilities. Also, by eliminating the need for emergency truck rolls, the platform reduces O&M (operational and maintenance) costs, facilitates repairs, and improves crew safety.

EdgeRestore is part of a larger, holistic approach developed by S&C to help utility operators improve the resilience of their grids as they face more frequent severe weather events.

S&C’s portfolio includes overhead and underground solutions designed to improve grid resilience and reliability from substation to load.