多因素条件下变压器自粘换位导线抗弯能力试验及评估

Research and Evaluation of Bending Resistance of Epoxy Continuously Transposed Conductors in Transformers Under Multi-factor Conditions

绕组幅向和轴向弯曲应力是表征变压器抗短路能力的关键指标,其发生值计算需用固化系数折算,固化系数的取值十分重要。提出了适用于自粘换位导线幅向和轴向固化系数的试验系统及方法,试验获得了不同温度、导线芯数、导线尺寸和有无衬纸等多因素条件下固化系数变化规律和取值范围。结果表明,温度和导线芯数是影响固化系数的主要因素,导线尺寸和有无衬纸几乎无影响。温度从20℃增加至120℃时,轴向固化系数平均值从3.4单调递减至1.0,幅向固化系数平均值从48.6单调递减至2.8。导线芯数从7根增大至79根时,轴向固化系数平均值降低了约35%,幅向固化系数呈先增大后减小的变化趋势,拐点通常出现在27~39根范围内。获得了多因素条件下固化系数修正结果,温度分别为105℃和120℃时,幅向固化系数取值范围分别为3.0~16.4、0.7~3.6,轴向固化系数取值范围分别为1.1~1.6、0.7~1.1。研究为变压器抗短路能力校核提供依据。

The radial and axial bending stresses of windings are key indicators to characterize the ability to withstand short-circuit of a transformer.The calculation of its value needs to be converted by the curing coefficient,and the value of the curing coefficient is very important.A test method for studying the radial and axial curing coefficient of epoxy continuously transposed conductors(CTC)is proposed.Through the tests,the rules of the curing coefficient under the conditions of different temperature,the number of transposed cores,the size of the cores,and the backing paper are obtained.The results show that the temperature and the number of transposed cores are the main factors affecting the curing coefficient,and the size of the cores and the backing paper have hardly any effect.When the temperature increases from 20℃to 120℃,the average value of the axial curing coefficient will decrease monotonically from 3.4 to 1.0,and the average value of the radial curing coefficient will decrease monotonically from 48.6 to 2.8.When the number of transposed cores increases from 7 to 79,the average value of the axial curing coefficient will decrease by about 35%,the radial curing coefficient shows a trend of first increasing and then decreasing,and the inflection point usually appears in the range of 27~39.The correction results of the curing coefficient under multi-factor conditions are obtained.When the temperature is 105℃and 120℃,the range of the curing coefficient in the radial direction is 3.0~16.4,0.7~3.6,and the range of the curing coefficient in the axial direction is 1.1~1.6,0.7~1.1,respectively.The research provides a basis for the check of the transformer’s ability to withstand short-circuit.