电缆弯曲对中间接头界面压力的影响规律研究

Effect Rule of Cable Bending on Interface Pressure Inside Cable Joint

由于电缆敷设条件限制,电缆中间接头可能发生一定曲率弯曲使其界面压力偏离预设值。针对上述问题,本研究基于力学理论建立了电缆中间接头发生不同程度弯曲后的过盈变化量数学模型。基于单轴拉伸试验结果和计算得到的Yeoh橡胶本构模型的模型参数,建立了一款110 kV硅橡胶冷缩型直通中间接头的有限元分析模型。结合数学模型和有限元分析结果对该接头过盈安装于不同尺寸电缆并发生不同程度弯曲前后的界面压力分布情况进行分析和验证。结果表明:当过盈安装的电缆中间接头随着电缆发生一定曲率的弯曲后,中间接头上表面中间区域的界面压力变大,两端的界面压力减小,而中间接头下表面中间区域的界面压力变小,两端的界面压力变大;应力锥根部至高压屏蔽管端部范围内的局部界面压力过大或者过小,易造成电缆中间接头局部力学性能劣化或者界面压力不足;应力锥工作区域内的局部界面压力不足和应力锥结构发生机械变形时,无法保证该区域界面电气强度和发挥其匀化电场的作用。

Due to the limitation of laying conditions,cable joint may bend at a certain curvature,making the interface pressure deviate from the preset value.Aiming at this problem,we built a mathematical model of magnitude of interference based on mechanics theory for cable joint after bending different degrees.A finite element analytical model for 110 kV silicone rubber cold-shrinkable straight-through cable joint based on the uniaxial tensile test results and the calculated model parameters of Yeoh model.Combined with the mathematical model and finite element analysis results,the interface pressure distribution of the cable joint,which was interference assembled on the different sizes of cable and bent different degrees,was analyzed and verified.The results show that when the interference assembled cable joint bends at a certain curvature with the cable,the interface pressure in the middle area of upper surface of the cable joint increases,and the interface pressure at both ends decreases;while the interface pressure in the middle area of lower surface of the cable joint decreases,and the interface pressure at both ends increases.While the local interface pressure from the root of stress cone to the end of high-voltage shielding tube is too large or too small,it may cause the mechanical properties of the cable joint deterioration or interface pressure insufficient.When the local interface pressure in the working area of stress cone is insufficient and the stress cone structure produces mechanical deformation,it is impossible to ensure the electrical strength of the interface and play the role in homogenizing the electric field.