1747 / 2020-10-01 15:28:41

Factors on Ohmic Loss of Converter Transformer Wall Bushing Plugging

wall bushing, plugging, ohm loss, FEM, factors

High Voltage and Insulation Technology > Other topics in high voltage and insulation technology

Under the condition of high current operation, ohm loss is an important factor for plugging overheating of UHV converter transformer. Based on FEM, the calculation model of wall bushing and plugging baffle is established, and the ohm loss of plugging baffle is calculated. By changing the inner and outer baffles are connected by grounding wire or not, the thickness of baffle, permeability, resistivity, and the contact type between baffles and bushing, the influence of the above factors on ohm loss of plugging baffles is analyzed. The results show that whether the inner and outer baffles are connected by grounding wire has little influence on the ohm loss of baffles. Therefore, the grounding wires can be ignored in the calculation model. With the increase of baffle thickness, the total ohm loss of the baffle increases, but the average ohm loss decreases significantly. When the thickness of baffle is small and the relative permeability changes in a small range, the influence of permeability on ohm loss is small. With the increase of the resistivity of the baffle, the ohm loss first increases and then decreases, and reaches the maximum value when the relative resistivity R_k is 0.5. When there is partial contact between baffles and bushing, the ohm loss of the baffle will also increase. Although the contact part between baffle and bushing is small, its average ohm loss is more than 10 times that of baffle, which is likely to cause local heating. In addition, the ohm loss of different types of contact parts is slightly different. The calculation results in this paper can provide theoretical basis and reference for the selection of plugging material and construction.