Industry knowledge analysis of PVC dipping insulation process for copper rows

Copper bar PVC-dipped insulation products refer to conductive components that form a continuous, dense polyvinyl chloride insulation layer on the surface of the copper bar through a dip-coating process. Its core structure is an internal copper conductor that closely adheres to the external PVC insulation layer. It combines the high conductivity characteristics of copper and the electrical insulation and protection functions of polymer materials. Unlike copper bars wrapped in heat-shrinkable sleeves, the plastic-impregnated insulation layer is adsorbed, leveled and solidified by molten PVC on the surface of the preheated copper bar. Therefore, there is no air gap between the insulation layer and the copper matrix, and the partial discharge starting voltage is higher. At the same time, the entire insulation layer has no seams, and the sealing reliability in humid or polluted environments is better than the casing solution. In terms of product form, Copper Busbar PVC Insulated covers the dipping process from straight copper bars to three-dimensional bent copper bars such as L-shaped, Z-shaped, and U-shaped. When it is necessary to achieve a "partially insulated, partially exposed" design on the same copper bar (for example, the connection areas at both ends need to be exposed to facilitate bolt tightening, and the middle span area needs insulation protection), selective coating can be achieved through the masking process before dipping.

 

Insulated Copper Busbar with Heat Shrink Tube represents another technical path - putting a prefabricated heat shrink sleeve on the copper busbar, and heating the sleeve to shrink it and tightly wrap the copper busbar. Its advantage is that it is flexible in construction and suitable for on-site modification, but theoretically, there is a small air gap inside the sleeve. PVC Heat Shrinkable Sleeves For Busbar are used as heat shrinkable sleeve materials and are widely used for insulation repair or local reinforcement of installed copper busbars. In electric vehicles and energy storage systems, Insulated Flexible Customized Busbar Insulating Tube combines PVC insulation with flexible copper bars or braided copper strips, allowing the product to be bent to fit into compact space layouts while providing reliable insulation protection. In addition, Customized Busbar Insulating Tube and Solid Insulation Tubing Busbar represent customized insulating pipe solutions, suitable for copper bar insulation with non-standard cross-sections or special temperature-resistant grade requirements.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The manufacturing of copper bar PVC dipped insulation starts with copper bar processing. The copper strip or plate is formed into the required shape through punching, bending, drilling and other processes. All edges need to be chamfered or deburred to prevent sharp edges from puncturing the coating during subsequent dipping and causing insulation weak points. The processed copper bars enter the pre-treatment process - first, burrs and flash are removed mechanically, and then the stamping oil and cutting fluid on the surface are removed by alkaline degreasing agent cleaning or ultrasonic cleaning. After cleaning, they are rinsed with pure water and dried thoroughly. Cleaned copper rows must be handled with clean gloves during operation to prevent contamination from hand sweat. For products that require partial insulation (such as both ends exposed and dipped in the middle), use high-temperature resistant tape or peelable paint to protect the areas that do not need to be coated before dipping. The shielded copper bars are hung on the plastic-impregnated brackets with iron wires or special hangers. The hanging points should be selected on non-critical surfaces or auxiliary parts that will eventually be cut off.

 

Then enter the preheating process. Put the suspended copper bars into the oven for heating. The preheating temperature and time depend on the size and heat capacity of the copper bars - small-sized copper bars require shorter preheating time, and large-section copper bars require a longer time to ensure uniform core temperature. The purpose of preheating is to make the copper bar absorb enough heat. When immersed in molten PVC, this part of the heat is transferred to the contacting dipping solution, so that the PVC can be evenly adsorbed on the surface of the copper bar and form an initial coating. Insufficient preheating will cause the coating to be too thick and uneven, while excessive preheating may accelerate the aging of the plastic dipping solution or oxidize the surface of the copper bar.

 

After preheating is completed, quickly immerse the hot copper bar into a dip-molding container containing molten PVC. The PVC inside the dip-molded container is kept within a specific temperature range to maintain proper fluidity. The immersion speed should be uniform and controllable to avoid bubbles or splashing. The immersion time determines the thickness of the initial coating - the longer the immersion time, the more PVC is absorbed and the thicker the coating. A single dip can usually achieve a coating thickness of 0.3 mm to 0.8 mm. If a thicker insulation layer is required, a multi-pass process of "dip-curing-re-dip" can be used. During the dip molding process, the coating thickness uniformity of Copper Busbar PVC Insulated is affected by the shape of the copper bus - the coating will be thinner at sharp corners and edges due to surface tension, and a compensation margin needs to be reserved in the design.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Interface bonding state between coating and substrate. After dipping, there is no visible air gap or delamination between the PVC coating and the surface of the copper bar. After cutting the product open and observing the cross-section, you can see that the coating adheres closely to the edges and flat areas of the copper bar. Even on the inside and outside of the bent corners, the coating shows no signs of peeling off or lifting. For properly pre-treated copper bars, the adhesion between the coating and the copper matrix can be tested by the cross-hatch method - cut a 1 mm × 1 mm square grid array on the coating surface, paste it with special tape and then tear it off. There should be no entire grid falling off at the edge of the grid.

 

Distribution characteristics of coating thickness. In the dip molding process, the coating thickness shows a certain distribution pattern in different parts. The coating thickness is the most uniform in the flat area of ​​the copper bar, and the deviation is usually controlled within ±0.1mm of the target thickness. Due to surface tension at edges and sharp corners, the coating will naturally become thinner. Therefore, sufficient fillet radius (usually R> 1.5 mm) needs to be reserved in the design of these locations to avoid the reduction in insulation strength caused by too thin a coating. The end of the copper bar is the weak link of the dipped coating. For products that require full insulation, the end coating needs to completely wrap the end face of the copper bar, and the thickness should not be less than 60% of the thickness of the flat area. For products that require partial exposure, there should be a clear and straight dividing line at the junction of the exposed area and the insulating area, and there should be no residual coating or contamination left after the masking material is removed.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copper row PVC-impregnated insulation products are widely used in complete power distribution devices, new energy electrical systems and rail transit power supply equipment. In low-voltage power distribution cabinets, control cabinets and capacitor compensation cabinets, the exposed parts of the main circuit copper bars (that is, the sections that are not connected to primary components and do not require heat dissipation) are usually insulated with PVC dipping to prevent phase short circuits caused by falling foreign objects or contact with maintenance tools. Especially in compact distribution boxes with shallow cabinet depths and tight phase distances, dipping insulation is an important means to meet electrical clearance requirements. In outdoor distribution boxes, chemical workshop electrical rooms and substations in coastal areas, where the ambient humidity is high and corrosive gases may exist, the continuous insulation layer of Copper Busbar PVC Insulated can effectively isolate the copper bar from contact with corrosive media and delay surface oxidation and electrochemical corrosion.

 

For products such as EV Battery Connectors and Battery Terminal Bus Bar that are used inside electric vehicle battery packs, the PVC-impregnated insulation layer needs to meet additional requirements for resistance to electrolyte corrosion and vibration and wear resistance - the battery will produce trace amounts of electrolyte volatiles during charge and discharge cycles, and the continuous vibration during vehicle driving will cause friction between the insulation layer and surrounding structural parts. Therefore, the adhesion and wear resistance of the impregnation layer are key indicators when selecting. Inside the energy storage container, the high-voltage connection copper bars between battery clusters usually use Insulated Flexible Customized Busbar Insulating Tube, because the energy storage system needs to arrange as many battery modules as possible in the limited container space, and the copper bars need to be bent to bypass the cooling pipelines and fire ducts, and the flexible Customized Busbar Insulating Tube layer can bend without causing insulation damage. In the field of rail transit, in the traction converter cabinets and auxiliary power cabinets at the bottom of the train, the copper bars may be accidentally touched by tools during installation and maintenance. The plastic-impregnated insulation layer provides additional operational safety protection.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We provide a full range of customized services from Busbar With PVC Insulation to flexible busbar insulation. You are welcome to provide copper bar drawings or samples. Our process engineers will issue a proofing plan and quotation after confirming the insulation requirements.