How to understand the impact of electrode and film assembly on the performance of low-frequency induction capacitors?

Why is assembly process the core guarantee of performance?
When the RAM 1250V 2000KVar 500Hz Low Frequency Induction Capacitor is in operation, the electrode and the dielectric film jointly construct an electric field environment. The uniformity of the electric field distribution is the cornerstone of the stable operation of the capacitor. When bubbles, wrinkles and other minor defects appear in the assembly of the electrode and the film, the electric field distribution will be seriously disrupted. The originally uniform electric field has a local electric field intensity that is too high due to these defects, which in turn causes partial discharge. This local discharge continues to erode the dielectric film, accelerates its aging, causes the insulation performance of the capacitor to deteriorate, and greatly shortens its service life.
Taking large-scale induction heating equipment as an example, when such equipment is in operation, the capacitor needs to withstand repeated shocks of high voltage and high current for a long time. In the application of medium-frequency induction furnace in a steel enterprise, due to the presence of fine wrinkles in the assembly of capacitor electrodes and film, partial discharge occurred after three months of operation, causing the insulation resistance to drop from the initial 10000MΩ to 1000MΩ, and the heating efficiency was reduced by 25%. The quality of the produced steel was also significantly affected, and problems such as uneven heating and inconsistent surface hardness occurred, with direct economic losses of hundreds of thousands of yuan. This shows that under such harsh working conditions, even extremely small assembly defects may become the fuse of equipment failure. Ensuring that the electrode and the film fit tightly and evenly and eliminating any possible defects are necessary prerequisites for ensuring the stable performance of low-frequency induction capacitors and are an insurmountable key checkpoint in the entire manufacturing process.
In the assembly of electrodes and films, the matching degree of different materials is also crucial. The roughness of the surface of the polypropylene film and the flatness of the aluminum foil will affect the contact area between the two. Studies have shown that when the surface roughness of the film is controlled within Ra0.1 - 0.3μm and the flatness deviation of the aluminum foil is within ±0.002mm, the contact resistance between the electrode and the film can be reduced to below 0.01Ω, which can effectively reduce power loss and improve capacitor performance.
How does the winding process achieve high-capacity manufacturing?
The winding process is a key assembly method for low-frequency inductive capacitors to achieve high capacity. This process forms a compact capacitor core by alternately winding high-purity aluminum foil electrodes and polypropylene films layer by layer. In this process, advanced automation equipment plays a vital role, which can accurately control the tension and speed during the winding process.
Accurate control of tension is the key to ensuring that each layer of electrode fits tightly with the film. The tension control equipment is usually driven by a servo motor and equipped with a high-precision tension sensor to control the tension fluctuation within ±1N. If the tension is too large, the film may be thinned or even broken; if the tension is too small, it is easy to wrinkle or relax, resulting in a gap between the electrode and the film, affecting the performance of the capacitor. Through high-precision tension control, combined with high-quality polypropylene film and high-purity aluminum foil with micron-level thickness (such as 4μm-8μm), the effective area of ​​the capacitor core can be greatly increased in a limited space, thereby achieving large-capacity storage.
In the power system of a large industrial park, due to the presence of a large number of inductive loads such as motors and transformers, the system power factor has been lower than 0.8 for a long time. After reactive compensation using low-frequency inductive capacitors manufactured by the winding process, the system power factor is increased to more than 0.95, and the line loss is reduced by 30%, which can save the park millions of yuan in electricity bills each year. These large-capacity capacitors, with their powerful energy storage and release capabilities, ensure the stability and efficiency of the power supply in the entire industrial area.
The number of winding layers and diameter in the winding process will also affect the performance of the capacitor. When the number of winding layers reaches more than 500 layers and the winding diameter is controlled at 100mm-150mm, the capacitance deviation of the capacitor can be controlled within ±3%, which can meet the accuracy requirements of most industrial scenarios for large-capacity capacitors.
How does the lamination process achieve a balance between performance and space?
For application scenarios with extremely stringent requirements on size and performance, the lamination process shows incomparable unique advantages. The lamination process precisely stacks multiple layers of aluminum foil electrodes and polypropylene films in sequence. After the stacking is completed, a series of complex processes such as high temperature and high pressure curing are used to tightly combine the layers into a stable whole.
From the perspective of electrical performance, the lamination process has obvious advantages compared to the winding process. In the actual application of a semiconductor chip manufacturing company, the low-frequency inductive capacitor manufactured by the lamination process has a dielectric loss tangent value (tanδ) of only 0.001, while the tanδ value of similar products using the winding process is 0.003, and the dielectric loss of the lamination process product is reduced by 66%. This not only improves the electrical stability of the capacitor, but also reduces its energy loss during operation and improves overall efficiency. In the semiconductor chip manufacturing process, a stable power supply is the key to ensuring the accuracy of the chip manufacturing process. The low-frequency inductive capacitor manufactured by the lamination process can provide a pure and stable power supply for such equipment, ensure the precise control of various parameters in the chip manufacturing process, and ensure the high-quality production of chips.
In terms of space utilization, the stacking structure is highly flexible. For example, the capacitor is required to meet the working voltage of 500V and the capacitance of 1000μF while the volume does not exceed 50cm³. The stacking process is adopted to successfully control the volume of the capacitor to 45cm³ by adjusting the number of stacking layers (30 layers) and optimizing the size design, meeting the strict requirements of the project for high voltage, large capacity and small volume. The low-frequency inductive capacitor manufactured by the stacking process provides a solid guarantee for the stable operation of the equipment in the electronic system of aerospace equipment with extremely high requirements for equipment integration and extremely limited space.
The interlayer insulation treatment in the stacking process is also key. At present, vacuum coating technology is often used to coat a 0.1μm - 0.3μm thick insulating layer on the surface of each layer of aluminum foil, which can make the interlayer insulation resistance reach more than 10¹²Ω, effectively prevent interlayer short circuits, and improve the reliability of capacitors.