Case Study: S&C Electric Company

S&C Electric Company

Chicago-based S&C Electric Company (hereby S&C) began as Schweitzer and Conrad, Inc in 1911. Beginning as an engineering company for preventing fires from high-voltage arcing, S&C in the modern era has focused on technology for improving grid reliability and resilience and modernization of aging infrastructure1 

EdgeRestore® Underground Distribution Restoration System

One major argument against undergrounding residential distribution (URD) circuits is that while placing wires underground is more reliable, if there are any faults in the underground wires, they are much more difficult and potentially expensive to fix. For instance, cable insulation, elbow connections, and splices wearing down are a normal part of the aging process for undergrounded lines. Under normal circumstances, such a fault would result in a permanent power outage which requires a crew to check each transformer to manually test for the fault. Not only does this expose crews to medium voltage (up to 35kV), but it also runs the risk of turning a defected transformer back on, possibly causing damage to the transformer, injuring the mechanics, and creating more outages2. Once the fault is located, a second crew is then deployed to fix the fault. Combined, this process can take many hours and result in long periods without power. 

EdgeRestore is a piece of undergrounding equipment that alleviates these concerns by automatically locates the fault and reroutes power through an alternate source in under a minute, eliminating the need for the first emergency crew entirely and preventing any power outages. When a voltage loss happens, circuit interrupters are triggered to open. The nearest interrupter to the electrical fault remains open, while the rest of the downstream interrupters engage in an automated communication process via powerline carrier technology. In residential neighborhoods with physical obstructions, powerline carrier technology is ideal because it does not require a direct line of sight, as opposed to other communications technologies like micro and radio waves.  

Once this communication is complete, the “Normally Open” EdgeRestore interrupter closes3. This action results in the restoration of power from an alternate source to all customers who were affected by the voltage loss. The secondary crew will then need to come fix the fault, but the elimination of the emergency crew leads to a reduction in the duration of power outages, a decrease in operation and maintenance (O&M) expenses, and a lower level of occupational risks or hazards.  

EdgeRestore is a “smart switch” that fits directly into already-existing residential transformers. Specifically, it is positioned between the bushing well, which is a component that provides electrical insulation, and the primary cable connections within the transformer. This integration with existing equipment means that no new structures that may detract from the visual appeal of an area need to be built.