The moisture-proof performance of a composite shielded insulated tubular busbar body directly affects its electrical insulation stability and operational reliability. Therefore, comprehensive optimization from multiple dimensions, including material selection, structural design, sealing processes, and environmental control, is necessary to construct a long-lasting moisture-proof system.
The moisture resistance of the main insulation material is fundamental to moisture-proof performance. Composite shielded insulated tubular busbar bodies typically use polytetrafluoroethylene (PTFE) as the main insulation layer. This material possesses excellent chemical stability and low water absorption, maintaining its insulation performance over long periods in high-humidity environments. To further enhance moisture-proof performance, nano-modified PTFE composite materials can be used. By filling these layers with nanoparticles, the gaps between molecules are reduced, lowering the rate of water vapor permeation. Simultaneously, adding a water-blocking buffer layer outside the insulation layer, such as an expandable water-blocking tape or a high-density polyethylene sheath, can form a double water-blocking barrier, effectively preventing external moisture intrusion.
The sealing structure design is a crucial aspect of moisture-proofing. Composite shielded insulated tubular busbar bodies must employ a fully sealed structure to ensure no gaps between the conductor, insulation layer, and shielding layer. Conductor joints and fixing bolts must be sealed with a special release agent and insulating caps to prevent moisture penetration along the metal surface. End seals should use heat-shrink tubing or cold-shrink tubing, combined with sealant, to ensure no leaks at the connection with cables or equipment. Furthermore, waterproof end caps should be designed at both ends of the tubular busbar body to prevent moisture from entering the interior through the ports.
The integrity of the shielding layer and grounding system indirectly contributes to moisture protection. The shielding layer of the composite shielded insulated tubular busbar body typically uses woven copper mesh or metallized film. It is essential to ensure the shielding layer is continuous without breaks and to achieve potential equalization through low-resistance grounding. Damage to the shielding layer or poor grounding can lead to localized electric field concentration, causing insulation aging or corona discharge, thus compromising moisture protection performance. Therefore, the shielding layer resistance value must be tested regularly to ensure it meets design requirements.
Environmental control during installation is an external guarantee of moisture protection. The composite shielded insulated tubular busbar body should be avoided in humid environments, locations with high concentrations of corrosive gases, or poorly ventilated areas. When laying cables in trenches or tunnels, drainage slopes and collection wells must be installed, along with automatic drainage devices. In coastal or high-humidity areas, a hydrophobic coating, such as fluorocarbon coating or silane impregnating agent, can be applied to the surface of the tubular busbar to create a superhydrophobic surface, reducing moisture adhesion.
Moisture-proofing measures during operation and maintenance should be a routine mechanism. Regularly check the surface of the tubular busbar for condensation or water stains. If the insulation surface is found to be damp, immediately blow dry air or use localized heating to dehumidify. For tubular busbars that have already become damp, internal moisture can be replaced by injecting dry nitrogen or deep drying with a portable dehumidifier. Simultaneously, a moisture-proofing record should be established, recording parameters such as ambient humidity and insulation resistance to provide a basis for subsequent maintenance.
Refined manufacturing processes are an inherent guarantee of moisture-proof performance. During production, the extrusion temperature and cooling rate of the insulation layer must be strictly controlled to avoid micropores or cracks within the insulation layer due to process defects. The conductor surface must be polished to remove burrs and sharp points, preventing concentrated electric fields that could lead to partial discharge. In addition, the finished product needs to undergo high-pressure water immersion testing or salt spray testing to verify its sealing and insulation performance under extremely humid environments.
Through the comprehensive application of material upgrades, structural optimization, environmental control, and process improvements, the moisture-proof performance of composite-shielded insulated tubular busbar bodies can be significantly improved. For example, after a substation adopted a nano-modified polytetrafluoroethylene insulation layer and a double-sealed tubular busbar body, it operated for many years in a high-humidity coastal environment, and the insulation resistance remained stable at a high level, with no failures caused by moisture, verifying the effectiveness of the moisture-proof solution.
