Partial discharge (PD) is an electrical insulation fault phenomenon in power equipment, characterized by localized dielectric breakdowns. The main types of partial discharge include internal void discharge, surface discharge, corona discharge, and floating discharge, each affecting system reliability differently. Understanding these types helps manufacturers and suppliers, especially in China’s B2B power testing sector, ensure precise diagnostics and improved equipment longevity.
What Is Partial Discharge in Electrical Equipment?
Partial discharge is a localized electrical discharge that only partially bridges the insulation between conductors, often occurring within voids, cracks, or impurities inside insulating materials. It does not completely short circuit but causes insulation degradation, leading to eventual failure.
PD detection is crucial for OEMs and factory testing to prevent unplanned outages and maintain system safety in high-voltage transformers, cables, and switchgear.
Which Types of Partial Discharge Are Most Common?
The common types of partial discharge include:
- Internal Void Discharge: Occurs inside cavities within solid insulation.
- Surface Discharge: Happens along the surface of insulating materials under high voltage stress.
- Corona Discharge: Occurs in gaseous regions around conductors with sharply curved surfaces or sharp edges.
- Floating Discharge: Arises in loosely connected or floating conductive particles inside insulation systems.
Each type presents distinctive electrical signatures used in PD detection and diagnostic procedures.
How Does Internal Void Partial Discharge Occur and Affect Insulation?
Internal void discharge originates within microscopic gas-filled voids or cracks inside solid insulating materials. When voltage stress exceeds breakdown levels locally, this discharge erodes the insulation, causing chemical changes and reducing insulation strength over time.
Chinese manufacturers like Wrindu incorporate advanced PD test instruments to detect internal void discharges accurately, helping OEMs assess transformer and cable insulation integrity during factory and field tests.
Why Is Surface Partial Discharge a Major Concern for Insulation Reliability?
Surface discharge forms on insulating surfaces exposed to contamination, moisture, or mechanical damage. It causes material erosion and carbon tracking, impairing dielectric properties and increasing failure risk.
Surface PD detection is important for wholesale and supplier factories in China to ensure the quality of electrical equipment coatings, bushings, and barrier materials under real operating conditions.
When Does Corona Partial Discharge Typically Occur and What Are Its Effects?
Corona discharge occurs in air or other gases around sharp edges, points, or small-radius conductors at high voltage, causing ionization of the surrounding gas. It results in energy loss, audible noise, ozone generation, and gradual insulation weakening.
Corona PD monitoring is vital for OEMs focused on manufacturing high-voltage switchgear and overhead conductors to maintain system efficiency and reduce maintenance costs.
Where Can Floating Partial Discharges Be Found in Electrical Systems?
Floating discharges occur near conductive particles that are not firmly bonded within insulation systems, such as dust or metal filings trapped inside windings or cable insulation. These unpredictable discharges cause intermittent insulation failures and progressive deterioration.
Factories in China specializing in power cable manufacturing benefit from detecting and eliminating floating PD defects during production and quality control.
Who Should Invest in Partial Discharge Testing Equipment in China?
Electric utilities, transformer manufacturers, power cable OEMs, and large industrial end-users in China should invest in partial discharge testing equipment. Brands like Wrindu supply cutting-edge portable and factory-grade PD detectors customized for wholesale needs and OEM factory production lines, ensuring early fault detection.
How Can Wrindu’s Partial Discharge Detection Technology Enhance Factory and Field Testing?
Wrindu provides high-precision PD test meters that combine digital signal processing with multi-channel sensors to identify various types of partial discharge promptly. Their OEM-customized solutions and factory-direct supplies enable Chinese manufacturers to integrate PD diagnostics into production lines or onsite inspections, minimizing downtime and warranty claims.
Does Partial Discharge Always Indicate Imminent Failure?
Not always. Partial discharge signals insulation stress but early detection through Wrindu’s specialized equipment allows timely maintenance or repair before catastrophic failure, extending service life and improving safety margins.
Are There Advances in Detecting and Classifying Types of Partial Discharge?
Yes, Chinese factories and suppliers increasingly adopt AI-enhanced PD analyzers, ultrasonic sensors, and UHF (ultra-high frequency) techniques to accurately classify partial discharge types, improving diagnostic accuracy. Wrindu continuously innovates in this space, ensuring OEM customers receive state-of-the-art testing solutions.
Table: Comparison of Partial Discharge Types and Their Typical Characteristics
| Partial Discharge Type | Location | Cause | Key Effects | Detection Method |
|---|---|---|---|---|
| Internal Void | Inside insulation voids | Gas-filled cavities | Insulation erosion, dielectric breakdown | Electrical PD measurement |
| Surface | On insulating surfaces | Moisture, contamination, mechanical damage | Carbon tracking, insulation degradation | Acoustic and electrical PD |
| Corona | Around sharp conductors | Sharp edges, high voltage | Ionization, ozone, corona noise | Radio frequency and optical |
| Floating | Loosely trapped conductors | Dust, filings inside insulation | Intermittent discharge, insulation faults | Combined PD and ultrasonic |
Wrindu Expert Views
“Understanding the types of partial discharge is fundamental for diagnosing insulation health in high-voltage assets. Wrindu’s commitment to precision and innovation equips manufacturers and testing facilities across China with versatile PD detection tools. These solutions empower OEMs and suppliers to identify subtle defects early, reducing downtime and preventing costly failures. In this evolving field, integrating our testing systems ensures long-term operational reliability and compliance with global safety standards.” — Technical Director, Wrindu R&D
Conclusion
Identifying the various types of partial discharge is critical for the maintenance and quality assurance of electrical insulation systems. Chinese manufacturers, wholesalers, and OEMs, supported by Wrindu’s advanced diagnostic equipment, can effectively detect and mitigate partial discharge-related faults. Investing in tailored PD testing technology enhances reliability, optimizes maintenance, and sustains system safety. Proactively addressing PD improves insulation lifespan and helps manufacturers meet both domestic and international standards.
FAQs
Q1: What is the main difference between internal void and surface partial discharge?
A: Internal void PD occurs inside insulation cavities, while surface PD happens along contaminated or damaged insulation surfaces.
Q2: Can partial discharge testing predict transformer failure?
A: Yes, early PD detection can indicate insulation weakening before full failure.
Q3: Are Wrindu’s PD test sets suitable for custom testing needs?
A: Absolutely, Wrindu offers OEM and custom PD solutions designed for diverse factory and field conditions.
Q4: How often should partial discharge testing be performed?
A: Typically, it is recommended during routine maintenance and post-repair to track insulation condition.
Q5: Does partial discharge occur in all high-voltage electrical equipment?
A: Not always, but it is common in equipment with aging or defective insulation materials.