| Medium voltage switch cabinet is a closed metal switch gear, and switch cabinet internal fever has become one of the most common fault in the power accident along with the load increasing. The long running of the connection part of the switch cabinet leads to aging, loosen, so that the increasing contact resistance becomes the major cause of switch cabinet internal fever. Memory alloy material can automatically change shape after heating temperature and the deformation can produce larger restoring force. When the gasket and spring made of memory alloy material were used in the switch cabinet, both the contact resistance of the switch cabinet and the temperature rise of the contact resistance of the switch cabinet reduced by the temperature profile of the memory alloy, which is very significant to improve the safety of the operation of the switch cabinet.Based on the temperature profile of the memory alloy, the temperature field of the vacuum switch cabinet which applied memory alloy gasket and spring was simulated by using the finite element simulation analysis technology, which provided reference for using memory alloy material to reduce the effect of the switch cabinet temperature.The main research work and conclusions are as follows:First chapter: the research background, significance and research status and research were described. The main reasons for temperature rise fault in vacuum switch cabinet were analyzed, and the main ideas and research content in this paper were proposed based on the research status of temperature field simulation analysis of switch cabinet.Second chapter: the contact resistance, heat transfer and finite element analysis were studied. For the contact resistance theory, the composition of the contact resistance and the impact factors of the contact resistance were mainly analyzed. For heat transfer theory, three kinds of heat transfer and three kinds of boundary conditions of finite element thermal analysis were mainly analyzed.Third chapter, the basic characteristics of memory alloy materials were studied. The relationship between the stress and the temperature of the memory alloy was studied by tests, and the effect on reducing the contact resistance was analyzed from the material properties of memory alloy.Fourth chapter: The copper joints with the memory alloy gasket and the common gasket were respectively simulated. According to the experimental results, the simulation model was adjusted and the error was controlled within 5%. With the accurate simulation model, the temperature rise of the memory alloy gasket and common gasket were contrasted and analyzed to verify the effect of reducing temperature rise with the memory alloy gasket.Fifth chapter: The contact of the plum blossom in the circuit breaker with the memory alloy spring and the common spring were respectively simulated. According to the experimental results, the simulation model was adjusted and the error was controlled within 5%. The temperature rise of the contact of the memory alloy spring and the common spring were contrasted and analyzed, and the effect of memory alloy spring for reducing the temperature of the contact of a single phase circuit breaker was verified.Sixth chapter: The temperature field of the whole switch cabinet was simulated and analyzed. When the memory alloy material was applied on 12 kV 3150A vacuum switch cabinet, the effect of reducing temperature rise was contrasted and analyzed with the accurate simulation model. The applicability and accuracy of the simulation model were tested. |
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