Transformer Loss of Oil Lockout (LOL) Enhancing Grid Resiliency Against Physical Attacks

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…