Does an automotive wiring harness possess resistance to corona or partial discharge?
Publish Time: 2025-12-09
In modern automobiles, especially new energy vehicles, the widespread use of high-voltage components in electrical systems places unprecedentedly stringent demands on wiring harnesses. As voltage levels continue to rise, corona discharge and partial discharge (PD) are increasingly becoming hidden threats to the long-term reliability of wiring harnesses. Therefore, whether an automotive wiring harness possesses resistance to corona or partial discharge is no longer merely a matter of material properties, but a core technical indicator concerning the safety and lifespan of the entire vehicle.Corona and partial discharge typically occur in areas of high electric field strength, such as conductor edges, micropores within insulation layers, impurities, or interface defects. When the voltage is sufficiently high, even if the insulation material as a whole is not broken down, air or air gaps in localized areas may be ionized, producing minute but continuous discharge phenomena. Although invisible to the naked eye, this discharge releases high-energy electrons and ozone, gradually eroding the insulation material, forming carbonized channels, and ultimately leading to insulation failure, short circuits, or even fires. This risk is significantly amplified in high-voltage platforms of 800V and above, especially in high-altitude areas—where thin air makes discharge more likely. Traditional low-voltage wiring harnesses, due to their lower operating voltage, almost do not require consideration of such issues. However, high-voltage wiring harnesses must be protected through a three-pronged approach: materials, structure, and manufacturing processes. First, the insulation material itself must possess high dielectric strength and a low dielectric constant to reduce electric field concentration. More importantly, the material must be dense and non-porous to prevent the existence of tiny air gaps that could be ionized. Therefore, high-end high-voltage cables often use high-performance materials such as cross-linked polyolefins (XLPO), thermoplastic elastomers (TPE), or fluoropolymers, and employ ultra-clean extrusion processes to ensure a uniform and defect-free insulation layer.Second, the design of the conductor and shielding layer is crucial. A smooth conductor surface reduces electric field distortion; while a fully covered metal braided or aluminum foil shielding layer not only suppresses electromagnetic interference but also evens out the electric field distribution, preventing excessively high local field strength. Some advanced designs also add a semiconductor layer between the insulation and shielding layers to further smooth the potential gradient and fundamentally suppress discharge initiation.Furthermore, cleanliness control during manufacturing and the quality of terminal crimping are equally critical. Even the smallest burr, dust, or crimp gap can become a discharge initiation point. Therefore, high-voltage wiring harness production is typically carried out in controlled environments, employing automated inspection methods to screen for potential defects.It is important to note that "corona resistance" is not a one-time solution. Long-term thermal cycling, vibration, or chemical corrosion can induce new microcracks or interface delamination during use, reintroducing the risk of discharge. Therefore, high-quality wiring harnesses must also possess good aging resistance and mechanical stability to ensure insulation integrity throughout the entire vehicle's lifespan.Finally, the industry has established specialized testing methods (such as the IEC 60270 standard) to evaluate partial discharge initiation and extinction voltages. Truly reliable high-voltage wiring harnesses must pass rigorous PD testing under simulated vehicle operating conditions, proving that they will not experience harmful discharges during their expected lifespan.In conclusion, the corona and partial discharge resistance of automotive wiring harnesses is the invisible cornerstone of high-voltage safety. It is not visible in appearance but is deeply rooted in the molecular structure of the materials and the precision of manufacturing. In today's surging wave of electrification, only by perfecting this "invisible protection" can we ensure peace of mind with every acceleration and reliability for every long journey.
