Summary
High-voltage transformers are critical to grid reliability but highly vulnerable to physical attacks due to their exposed placement and long replacement lead times. Recent incidents, including the Metcalf sniper attack and coordinated assaults in multiple states, underscore the growing threat. Existing standards like NERC CIP-014 focus on substation-level security but do not provide automated, asset-level protection. Conventional transformer protection schemes detect electrical faults, not rapid oil-loss events caused by physical damage. To address this gap, ComEd developed the Loss of Oil Lockout (LOL) scheme, an autonomous system that isolates transformers before catastrophic internal failure occurs. The LOL design uses a progressive logic sequence based on three mechanical indicators—conservator tank level,
Read more Read lessBuchholz relay, and main tank level—to confirm oil-loss progression and issue a lockout command. Operating independently of SCADA, the scheme ensures resilience even during communication outages. ComEd’s approach offers a cost-effective safeguard that prevents internal destruction, reduces outage duration, and complements existing physical security measures. This innovation demonstrates how asset-level automation can significantly enhance grid resiliency against evolving physical threats.
Commonwealth Edison (ComEd), the primary electric utility in Illinois, serves a vast customer base of 4 million across the northern region, covering 70% of the state's population. The utility operates in an extensive area of 11,400 square miles and oversees more than 90,000 miles of power lines.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | A2_10750_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | United States of America |
| Study committees | |
| File size | 678 KB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
FITZGERALD Sean - ComEd, United States of America; GUREVICH Boris - ComEd, United States of America; LUTES Ty - ComEd, United States of America
Keywords
