A provincial electric utility in Canada is responsible for operating and maintaining medium- and high-voltage substations and transmission lines across a vast geographic area. Due to Canada's long, harsh winters and extreme temperature fluctuations, equipment insulation is highly susceptible to environmental stress. Corona discharge serves as an early warning sign of insulation deterioration. If left undetected, it accelerates the aging of organic materials, ultimately leading to flashovers or catastrophic equipment failure.
Historically, the utility relied on ultraviolet (UV) imagers for corona detection, but they faced significant operational limitations:
Prohibitive Costs: Professional UV imagers are highly expensive, making fleet-wide deployment impossible. They were utilized as shared regional assets, severely limiting access for everyday line patrol crews.
Daylight Interference: The intense reflection of sunlight off winter snow significantly degraded the performance of traditional UV imagers, restricting inspections to overcast days or twilight hours.
Limited Diagnostics: UV imaging only provided visual localization of the discharge. It lacked acoustic spectrum analysis and Phase Resolved Partial Discharge (PRPD) data, which are critical for evaluating the severity and type of the defect.
To overcome these inspection bottlenecks and optimize their budget, the utility deployed the Hertzinno HA3 acoustic camera across its regional substations.
Cost-Effective Scalability: Costing approximately 1/5th the price of a traditional professional UV imager, the HA3 allowed the utility to equip multiple maintenance crews using the same budget, achieving fleet-wide deployment.
Technological Advantages: Utilizing a high-sensitivity digital MEMS microphone array and advanced beamforming technology, the HA3 captures ultrasonic emissions. It is entirely immune to sunlight and snow glare, enabling true 24/7 inspection capabilities.
During a recent preventative maintenance cycle, the inspection team utilized the HA3 to scan transformer bushings, GIS terminals, and insulator strings from ground level.
Precise Anomaly Localization: In bright midday sunlight, without the need for scaffolding or lifts, inspectors scanned entire bays. From a distance of 15 meters, the HA3 accurately pinpointed abnormal ultrasonic emissions at the top of a 230kV transformer bushing, overlaying a real-time, color-coded sound map onto the visible-light image.
Intelligent PRPD Diagnostics: Using the HA3’s built-in analysis system, inspectors obtained the PRPD pattern of the discharge. The AI-based system automatically classified the defect as "corona discharge," ruling out surface or floating discharge, and confirming the specific node where ozone and nitrogen oxides were eroding the insulation.
Increased Inspection Frequency and Coverage: The reduced equipment cost put professional-grade detection into the hands of every frontline inspector, dramatically increasing the frequency and coverage of substation and line patrols.
Weather Independence: By eliminating daylight sensitivity issues, inspection schedules are no longer dictated by weather conditions or time of day, optimizing personnel deployment and operational efficiency.
Automated Reporting: After each inspection, the HA3 automatically generates digital reports containing visible-light photos, acoustic heat maps, and spectral data. This comprehensive data provides a direct foundation for Condition-Based Maintenance (CBM), effectively preventing unplanned outages.
