Study On Thermal Defect Mechanism And Protection Of Isolating Switch Static Contacts

High voltage isolating switch is the most widely high voltage electrical equipment in power system. Generally, the isolation switch is in a constant switching state and it is very likely to go unnoticed by the users. The universal lack of attention on the isolating switch may lead to frequent overheating of the conducting joint.In this work, GW6A-252 type isolating switch static contacts were selected as the research target, the structure, material, working environment and operation condition were studied. The possible mechanism of overheating was explored as well. Physical model established by SolidWorks was imported to ANSYS Workbench, the stress distribution under normal loading was simulated by ANSYS Workbench software. The overheating problem of isolating switch static contacts was solved by the structure optimization and protective coating.Experimental results showed that the congenital structural design and the environmental corrosion may be the leading courses of the overheating of isolating switch static contacts. Accordingly, two structural optimization strategies were proposed. First,Optimization of the original structure: small groove with the same direction of aluminum conductor were manufactured, making the full cooperation of the single strand of aluminum conductor with small groove. Second, Crimp connection was chosen as a replacement of the conventional bolted connection between the aluminum and clamp. Copper aluminum transition clamp connection was used on conductive rod and aluminum conductor. In order to solve the problem of environmental corrosion, outer protective materials which reached the national standards were prepared and characterized. Experimental results showed that there was apparent improvement in the performance: a maximum decrease of 47.2% in contact resistance and a 20-50℃ lower operation temperature could be realized by the optimization mentioned above. Protective material showed high performance, which could be used in a variety of fields, such as grid and high-speed railway.