How does the multilayer structure of composite paper practically enhance its insulation performance?
Publish Time: 2025-10-02
At the heart of power equipment, insulation materials silently yet crucially safeguard safety. They isolate high-voltage currents, prevent energy surges, and ensure stable operation. Composite paper, an advanced insulating material, is unique not only in the type of fibers used, but also in its meticulously designed multilayer structure. This structure is not merely a simple layering; it's a synergistic system that, through interlayer coordination, significantly enhances overall electrical performance and long-term reliability, making it an indispensable material for modern high-voltage, high-temperature equipment.The primary advantage of the multilayer structure lies in its optimization of electric field distribution. Under high voltage, the electric field is not uniform; it concentrates at conductor edges or structural discontinuities, forming high-field regions prone to partial discharges—the starting point of insulation degradation. Composite paper, through its layered composition of different materials, adjusts the overall dielectric constant and conductivity, resulting in a more uniform electric field. High-insulation layers bear the primary voltage stress, while transition layers mitigate field concentration, preventing stress concentration. This "graded" design, like a smooth path for current, reduces partial discharges and extends the material's lifespan.Secondly, the multilayer structure effectively enhances breakdown resistance. A single material, under prolonged electrical stress, may develop conductive paths due to microscopic defects or impurities, leading to breakdown. The interfaces between layers in composite paper act as physical barriers. When an electrical tree or discharge channel develops in one layer, it encounters the interfaces of different materials, disrupting or diverting its path. Variations in interlayer bonding, fiber orientation, or resin impregnation can all disrupt the continuity of the discharge path, forcing it to expend more energy to penetrate. This "layered defense" mechanism significantly improves the overall breakdown strength.Complementary mechanical properties are also crucial in multilayer design. Some fibers have excellent electrical insulation but lack mechanical strength; others are strong and flexible but have poor dielectric properties. By combining high-insulating layers with high-strength support layers through lamination, composite paper ensures both excellent electrical performance and resistance to tearing, delamination, or wrinkling during winding, pressing, or thermal expansion and contraction. For example, in motor slot insulation, composite paper must withstand friction and pressure during winding. Its multi-layered structure allows it to maintain a thin profile while possessing sufficient abrasion resistance.Heat resistance and aging resistance also benefit from the multi-layered design. High temperatures are the main cause of insulation material degradation; single-material insulation may experience molecular chain breakage or oxidation under prolonged heat exposure. Composite paper addresses this by incorporating a high-temperature resistant layer (such as aramid fiber) with conventional fibers, forming a thermal barrier to slow heat transfer. Furthermore, different materials age at different rates; the multi-layered structure prevents a single weak point from causing total failure. Even if one layer begins to degrade, the remaining layers maintain basic insulation function, providing warning time for equipment maintenance.Moreover, the multi-layered structure enhances resistance to environmental factors. Moisture, chemical contaminants, or mechanical vibrations can penetrate from the outside; a single-material insulation, once damaged, rapidly loses its insulating properties. The outer layer of composite paper can be designed as a dense, waterproof, or corrosion-resistant layer to protect the sensitive inner layers, while the intermediate layers focus on electrical performance. This "division of labor" structure ensures stability under complex operating conditions.Ultimately, the multi-layered structure of composite paper is a system-level performance enhancement strategy. It doesn't rely on the absolute performance of a single material, but achieves a synergistic effect through scientific combination. Each layer has its role—as a barrier, a support, or a buffer—working together to form a robust and intelligent insulation barrier. Between the windings of transformers, on the stator slots of motors, and between the plates of capacitors, this silent, layered structure reliably safeguards the safe operation of power systems.
