±800 kV输电线路预绞式悬垂线夹断裂分析

Fracture Analysis on Helical Suspension Clamp of ±800 kV Transmission Line

预绞式悬垂线夹因在结构、性能和节能等方面的显著特点被广泛应用。针对某±800 k V输电线路地线预绞式悬垂线夹断裂问题,开展材质检测、机械强度试验和力学计算,检测发现线夹单侧悬垂角为10°,不符合DL/T 763—2013要求。张力试验表明40°出线角时线夹极限张力约为38 k N;且当线夹悬垂角一定时,出线角越大,线夹悬垂套壳承受极限张力越小。脱冰跳跃动力计算发现当前档80%及以上地线脱冰时,后侧线夹出线角增大,对应的地线张力达到线夹的极限荷载。指出线夹由于悬垂角偏小,地线脱冰跳跃致使其断裂。提出对重冰区预绞式悬垂线夹套壳底部变形检查建议。

The helical suspension clamp is widely used in terms of structure performance, energy conservation. The failure helical suspension clamp in a ±800 kV transmission line was investigated by means of material property testing, mechanical strength test and mechanical calculation. It was found that the suspension angle of the clamp is 10 degrees, which do not conform to the requirements of the DL/T 763-2013. The tension tests indicated that the ultimate strength of the clamp is about 38kN while the outlet angle is 40 degrees. When the clamp＇s suspension angle is a constant value, the greater the outlet angle of clamp, the smaller its ultimate strength. The dynamic response of ice shedding-caused vibration was analyzed by finite element method （FEM）. The results showed that when ice shedding occurs on 80% and above length of the front span groundwire, the outlet angle of back clamp will increase, and the corresponding tension of ground wire would reach the ultimate strength of clamp. It was pointed out that clamp＇s fracture is the result of the ice shedding and its small suspension angle. It was suggested that the deformation inspection of helical suspension clamp should be carried out in heavy icing area.