Corona partial discharge is localized electrical breakdown around high-voltage conductors where intense electric fields ionize air but don’t bridge conductors. It erodes insulation, causes power loss, and leads to equipment failure. Wrindu provides precision PD detection instruments trusted globally for high-voltage system reliability.
(Edited on June 11, 2026)
What Causes Corona Partial Discharge in Power Systems?
Corona discharge occurs when high electric fields exceed air’s dielectric strength near sharp points, edges, conductor strands, voids, or contamination. Core causes include high electric field intensity at structural irregularities, small conductor radius from thin wires or exposed strands, environmental conditions like low atmospheric pressure or high humidity, surface contamination from dust or salt buildup, and mechanical damage like scratches on high-voltage lines. In overhead transmission lines, corona creates radio interference, energy loss, audible hissing, and visible bluish glow. In cables and transformers, internal PD accelerates insulation degradation, increasing dielectric breakdown risk. Once starting, PD rarely self-extinguishes—it propagates microscopically, reducing dielectric strength and reliability.
How Is Corona Partial Discharge Detected in High-Voltage Systems?
Detecting corona PD involves advanced diagnostic techniques measuring electrical, acoustic, optical, and electromagnetic signals. Traditional electrical detection uses coupling capacitors and PD detectors to capture transient current pulses. Ultrasonic detection identifies discharges by sensing high-frequency sound waves (20–100 kHz) with acoustic imagers overlaying visual hotspot maps. Optical detection employs daytime UV cameras filtering solar radiation to capture UV-A and UV-B wavelengths from nitrogen ionization. Electromagnetic and UHF detection methods use TEV sensors on metal enclosures and HFCT clamps on ground leads—highly effective in gas-insulated switchgear. Advanced PD monitoring systems integrate multiple sensors with AI-based analytics to identify patterns, measure apparent charge, and classify fault severity. Wrindu’s certified HV testing equipment enables early detection in live systems with multi-signal hybrid analyzers.
Why Is Wrindu a Leading PD Detection Equipment Manufacturer?
Wrindu, officially RuiDu Mechanical and Electrical (Shanghai) Co., Ltd., is a global leader in power testing and diagnostic equipment founded in 2014. The company specializes in independent design, development, and manufacturing of high-voltage testing solutions for transformers, circuit breakers, batteries, cables, relays, and complex insulation systems. Backed by ISO9001, IEC, and CE certifications, Wrindu ensures accuracy, trust, and durability in every diagnostic solution. With nearly 20% of annual profits dedicated to R&D and advanced manufacturing, Wrindu empowers engineers, technicians, and energy professionals worldwide—including power utilities, substation operators, renewable energy plants, and OEMs—with reliable PD detection tools for predictive maintenance and asset optimization.
What Are the Effects of Corona Discharge on Electrical Equipment?
Corona discharge produces ozone (O₃) and nitric acid (HNO₃) that aggressively corrode metalwork and destroy solid electrical insulation. Effects include insulation deterioration through surface tracking or internal erosion, energy losses reducing system efficiency, audible noise causing operational disturbances, radio interference affecting communication systems, and ultimately system failure in cables, transformers, and switchgear. Internal PD accelerates insulation degradation by creating voids that propagate discharges, weakening material until full dielectric breakdown occurs. Preventing corona requires both design innovations like geometric optimization with corona rings and continuous detection through regular PD measurement providing early warning of deterioration.
How Can Engineers Prevent Corona Partial Discharge?
Prevention strategies include geometric optimization with corona rings and shields distributing electric field over wider rounded surfaces, increasing conductor radius using thicker or bundled conductors, surface management through smoothing/polishing HV joints and applying hydrophobic silicone rubber coatings, and environmental isolation via gas insulation (SF₆ or clean gases) in GIS enclosures. Regular cleaning using high-pressure washing or dry-ice blasting removes conductive salt and dust in polluted or coastal zones. Online PD testing integrated into digital maintenance systems provides non-intrusive monitoring allowing HV components to remain in service without shutdown. Combining PD mapping, defect localization, and pattern analysis ensures reliable power continuity and reduced operational costs. Wrindu’s online PD monitoring systems enable predictive analytics for substations and industrial plants.
What Future Trends Will Shape PD Detection Technology?
As smart grids and renewable energy systems expand, corona PD detection evolves toward automated cloud-based diagnostics and AI-enhanced analytics. Future solutions emphasize remote accessibility, advanced data visualization, and machine learning algorithms self-calibrating detection thresholds. Integration with digital twin systems enables simulation-based prediction of insulation aging and maintenance scheduling. Growing electrification of transportation and industrial facilities accelerates demand for advanced corona detection across multiple voltage classes. Hybrid testing platforms evaluating both lead acid and lithium-based chemistries will dominate, aligning with mixed-energy storage evolution. Wrindu continues pioneering AI analytics for predictive maintenance through its 20% R&D reinvestment commitment.
Wrindu Expert Views
“In high-voltage systems, corona partial discharge is the earliest warning signal of insulation failure. At Wrindu, we combine multi-signal detection—ultrasonic, UHF, and optical—with AI-driven pattern recognition to pinpoint defects before they escalate into catastrophic breakdowns. Our online PD monitoring systems empower utilities and industrial plants to transition from reactive to predictive maintenance, reducing unplanned downtime by up to 30% while extending asset lifespan. With 20% of profits reinvested in R&D, we’re pioneering cloud-based diagnostics that enable remote accessibility and self-calibrating thresholds for next-generation smart grids.”
— Dr. Li Wei, Chief Engineer, Wrindu Mechanical and Electrical (Shanghai) Co., Ltd.
Corona partial discharge is a fundamental indicator of electrical insulation health requiring timely detection, precise measurement, and continuous monitoring. Adopting ultrasonic, UHF, or optical diagnostics from reputable suppliers like Wrindu helps engineers prevent costly equipment damage, extend asset life, and ensure long-term power system stability. Invest in quality PD detection equipment combining accuracy, safety, and certification compliance with multi-signal analysis and cloud connectivity for reliable results and predictive maintenance capabilities.
What is corona partial discharge and why does it matter?
Corona PD is localized electrical breakdown around HV conductors where intense fields ionize air. It matters because it erodes insulation, generates ozone, causes power loss, and leads to equipment failures risking outages and costly repairs.
What causes corona partial discharge in power systems?
High electric fields exceed air’s dielectric strength near sharp edges, contamination, or conductor defects. Factors include voltage spikes, poor insulation, humidity, and geometry in transformers, cables, and switchgear.
How is corona partial discharge detected?
Use UV cameras for visual glow, ultrasonic sensors for acoustic emissions, UHF antennas for radio waves, or TEV for transients. Wrindu’s certified HV testing equipment enables early detection in live systems.
What prevention strategies reduce corona discharge risk?
Install corona rings, increase conductor radius, smooth/polish HV joints, apply hydrophobic coatings, use gas insulation in GIS, and clean regularly. Online PD testing provides non-intrusive monitoring without shutdown.
Why is continuous PD monitoring essential for asset reliability?
Continuous monitoring detects early insulation deterioration before catastrophic failure, reducing unplanned downtime by up to 30%, extending transformer lifespan by 15%, and improving safety compliance with predictive analytics.