A potentially destructive phenomenon occurring in high voltage electrical systems is corona. Corona occurs when the air surrounding a conductor is ionized, causing an electrical discharge. Corona discharge represents a power loss, and can damage system components over time. Corona and arcing accelerate degradation of various components, and can indicate a number of factors which may cause an outage and/or safety issue. As insurance companies are recognizing corona detection as an important indicator of potential issues, predictive maintenance (PdM) practitioners have prioritized adding it to their PdM programs.

Scanning high voltage substations presents a potentially dangerous situation. Fortunately, non-intrusive technology exists to minimize the safety risks. Instead of opening up substation panels, creating an unnecessary risk of an arc flash incident, maintenance technicians can use ultrasound to detect corona discharge. Ultrasound equipment can be used safely by scanning seams and vent slots, leaving doors or covers in place. Ultrasonic equipment detects high frequency sounds produced by the disturbance in the ionized air, then translates them down into the audible ranges. The resulting sound is distinct: an erratic crackle or sizzle is heard when corona is present. This “crackle” greatly contrasts the normal hum of transformers or other electrical equipment. Once corona is detected, maintenance efforts can be planned to address flaws in the system.

Corona discharge represents a dangerous liability in high voltage systems. Take the time to safely diagnose potential issues using ultrasound, and avoid potential catastrophic failures.