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Copper connections are used for the joints of copper in the substation equipment rooms, while aluminum connections are used for those of aluminum. Copper-aluminum joint areas require the use of copper-aluminum transition type device clamps. Currently, flash welding and friction welding are widely used for manufacturing 110 kV copper-aluminum transition type device clamps in power systems. According to available information and investigations, the 110 kV copper-aluminum transition type clamps used in flash welding and friction welding can break at the copper-aluminum transition junction. The failure of such clamps can lead to Class A or Class B grid accidents, or even widespread power outages; it represents a serious safety hazard that is easily overlooked. 1 Welding process for 1110 kV copper-aluminum transition type equipment clamps 1.1 Flash welding Flash welding is a manufacturing process in which copper and aluminum sheets are rapidly melted under the action of high current, and then combined together due to mechanical pressure and forging forces. This method yields products with a high success rate and stable performance, and it has been incorporated into **standards. A bending test must be conducted before mass production: the aluminum sheet is clamped in a vise, with the weld located 8–12 mm away from the vise mouth, and then an adjustable wrench is used to clamp the upper copper part and bend it 180 degrees. No separation between copper and aluminum is considered acceptable. 1.2 Friction Welding: Friction welding is a manufacturing process in which copper and aluminum rods are rotated at high speeds, causing the welding surfaces of copper and aluminum to melt at high temperatures; subsequent pressure application and forging then bring copper and aluminum together. This method is widely used in the production of device clamps for wires with a cross-sectional area of 240 mm2 or less. The product has high strength, operates safely and reliably, with bending tests identical to those for flash welding. 1.3 Brazing Brazing is a processing method in which a thin copper sheet is bonded to an all-aluminum equipment clamp by heating with chemicals and then pressed together mechanically, thereby welding the copper sheet to the aluminum plate. This method features simple processing and reliable quality; it uses aluminum as the main material with only a small amount of copper. The product does not break even when affected by other conditions, making it the most reliable clamping device for copper-aluminum applications. In situations where copper resources are scarce, it is an ideal alternative to friction welding and flash welding. 2 The copper-aluminum transition form of 110kV copper-aluminum transition type equipment clamps: one method is the butt welding of aluminum plates and copper plates. Due to the complex welding process at the copper-aluminum transition joint, the welds are prone to cracking, and the high amount of copper used results in high product costs. Another approach involves brazing 1–2 mm thick copper sheets onto the surface of the aluminum plate; the device clamps are also made by brazing 1–2 mm thick copper sheets onto the aluminum surface to facilitate the transition between copper and aluminum. The clamps are primarily made of aluminum, which ensures good electrical performance while using very little copper, resulting in low production costs. Moreover, since the terminal board and the clamps form a single unit, their mechanical strength is ensured. It should be noted, however, that when drilling holes in the wiring board, the holes should be made in the copper surface. The two types of device clamps are essentially identical in function. 3 Analysis of the Causes of Fracture in 110 kV Copper-Aluminum Transition Equipment Clamps 3.1 Reasons Related to the Weldability of Materials and Welding Processes Copper and aluminum (especially aluminum) have poor weldability; even when welding materials of the same type, appropriate auxiliary methods are required to achieve good strength. For example, brazing requires welding flux, while welding aluminum necessitates shielding methods such as gas protection. The transition joint of copper-aluminum equipment clamps is a weld between two different metals; if flash welding or friction welding is used as the manufacturing process, the strength of the weld joint can, in an ideal scenario, only reach the strength level of aluminum, which is the metal with the lowest strength among the two base materials. Since it is not possible to form a complete and sufficient \"melting pool\" at the interface between the two base materials during welding, and moreover the melting point of aluminum is much lower than that of copper, their crystal structures do not achieve complete fusion with one another; the microstructure is uneven, and some cracks or fissures can even be seen with the naked eye. As a result, the strength of such interfaces is often significantly reduced, leading to fracture during shear or bending tests. The welding surface of the product is not clean, and the welding quality is unstable; it may break or come loose during impact or bending tests. 3.2 Environmental condition factors in welding: Processes such as flash welding require very strict control over process parameters during manufacturing, and there are potential sources of instability in product quality. The quality of the copper-aluminum weld interface can be affected by environmental factors such as high temperatures, vibration fatigue, and corrosion, which can lead to a decrease in mechanical strength. Factors such as salt spray, acidic gas corrosion, and harsh weather conditions can cause aging of the product surface, leading to uneven oxidation and subsequent product failure. 3.3 Load condition factors: During installation and operation, the wire clamp must withstand both the tensile force of the wire and the shear force. The joint formed by flash welding or friction welding has a small contact area; compared to brazing, it can be considered a \"line contact.\" The interfacial resistance at such joints is high, resulting in significant temperature rises. Moreover, the different coefficients of thermal expansion of copper and aluminum objectively worsen the stress conditions at the joint. Furthermore, the working torque acting on the interface can easily cause stress concentration, leading to fatigue fracture of the clamp. Since the mechanical strength of aluminum is lower than that of copper, it generally results in physical fracture occurring first in aluminum. 3.4 Long-term fatigue (current overload) operation: Due to the different expansion coefficients of aluminum and copper, as well as long-term overload and high-temperature heating, the product may break. 4 Conclusions and Recommendations The butt-welded clamp terminal plate and the clamp form a single unit, ensuring adequate mechanical strength. The brazed clamps experience working torque across the entire working surface during installation and operation; they can effectively overcome the drawbacks associated with the flash welding process, such as stringent requirements, significant influence from environmental factors, a small contact area between the components, poor stress conditions, and easy stress concentration at the joints. They also help to reduce the contact resistance and temperature rise of the clamps. It is recommended to use 110 kV copper-aluminum transition type device clamps manufactured by brazing instead of those made by flash welding or friction welding, in order to avoid accidents caused by the failure of device clamps produced using these latter welding methods.