Abstract: This paper describes the technical characteristics of the developed 10000kvar tandem assemblies, demonstrating the successful development of the product, its excellent technical performance, and its applicability. Keywords: Tandem assemblies, large capacity, technical characteristics 1 Introduction Task-assemblies, with their advantages of large capacity, small size, small footprint, and convenient installation and maintenance, are increasingly popular with users, and their market share is increasing year by year. Based on user requirements and advancements in power capacitor manufacturing technology, their capacity is also increasing, and the technical performance indicators of the products are improving. Xi'an Xidian Power Capacitor Co., Ltd. (hereinafter referred to as Xirong Company) supplied four 10Mvar tandem capacitors to Guizhou Provincial Power Company, which are the largest capacity full-film tandem capacitors in China, used in the Liping 220kV substation in Guizhou Province. Xirong Company, with 16 years of experience in producing tandem capacitors, adopted advanced design, process technology, and unique internal fuse protection technology, enabling the product's technical performance indicators to reach the leading level in China. 2. Product Technical Features 2.1 Capacitor Unit Considering the large capacity of the product, the capacitor unit is selected with a lower operating field strength than conventional products. All components within the capacitor unit are connected in parallel. The solid dielectric is a full-film dielectric, and the liquid dielectric is benzyltoluene with good low-temperature performance. The plates adopt a structure with one side protruding and the other side folded, which avoids the problem of high contact resistance in traditional lead-plate structures and improves the distribution of the electric field at the edge of the plates. The capacitor unit adopts a new internal fuse structure. When the fuse of an element blows, it has no effect on the surrounding fuses, avoiding the phenomenon of cluster explosions that easily occur when the fuse of the traditional internal fuse structure blows. 2.2 The entire integrated capacitor product has a three-phase common structure, consisting of several capacitor units connected in parallel and series. The body and the box cover are an integral structure. Insulation barriers are set between the phases of the capacitor to strengthen the phase-to-phase insulation and prevent phase-to-phase breakdown. The tank shell adopts a flat welded reinforcing rib and heat dissipation rib structure. Although the product capacity is large, the product loss is very small. Therefore, without the addition of purchased heat sinks, folding plates, etc., the temperature rise of the hottest spot of the product still meets the requirements. The product adopts a large oil tank structure, thus avoiding the problems of insufficient oil tank adjustment leading to oil overflow in summer and significant oil level drop in winter. The product is equipped with a pressure-type temperature controller to indicate the hottest oil temperature inside the tank and a pressure relief valve. The product undergoes external insulation testing at an altitude of 2000m, and a temperature rise test at 1.35Ω for no less than 48 hours. Capacitor capacitance deviation is controlled within 0-5%, all requirements exceeding the standard. In addition to the standard requirements, a load test of 1.1 times the rated voltage for 48 hours is added for each product. The integrated oil tank adopts a new process of overall shot peening, cleaning, and painting, significantly improving the surface coating quality compared to previous methods. After coating, the product adhesion has improved from level 3-4 to level 0-1. The product's fastener surface treatment utilizes the new Dacromet technology. The product's appearance is shown in Figure 1, and its main technical performance is shown in Table 1. [align=center] [/align] 3. Complete Set of Equipment The product is supplied as a complete set, including disconnecting switches, grounding switches, zinc oxide surge arresters, discharge coils, dry-type air-core series reactors, etc., designed for Class III pollution areas. Its appearance and electrical connections are shown in Figure 2. The complete set of equipment uses a three-pole disconnecting and four-pole grounding switch (with a grounding switch at the neutral point), and the reactors are air-core series reactors. On the power supply side, the device provides open delta voltage protection for the capacitors. For a device with a reactance rate of 6%, the protection setting is 2.91V; for a device with a reactance rate of 12%, the protection setting is 3.1V. 4. Conclusion Through this development of the 10Mvar all-film integrated capacitor, it is demonstrated that Xirong Company's experience in developing large-capacity integrated capacitors is mature. Its technical performance indicators are superior to conventional products, laying a solid foundation for the development of products with larger capacities. Currently, Japanese high-capacity products have reached a single-unit capacity of 40Mvar. I believe that developing a 20Mvar single-unit aggregate capacitor in China is feasible at this stage, and could be configured in a double-star configuration with neutral point unbalanced current protection. Of course, I hope the market will provide manufacturers with such opportunities, thus gradually narrowing the gap with foreign manufacturers.