输电线路防灾减灾安全销的设计

Design of safety pin to prevent disasters of transmission line

对型号为5A-ZM4铁塔进行极限承载力计算,确定塔线分离控制荷载并设计出过载保护金具安全销,当导线、地线上的覆冰厚度超过极限荷载所对应的覆冰厚度时,安全销能使塔线自动分离防止倒塔和断线。采用增量加载非线性有限元法计算安全销的极限承载力,与设计的塔线分离控制荷载吻合。通过分析荷载位移曲线知安全销随着荷载的增加由初始的线弹性状态逐渐过渡到极限塑性破坏状态;并判断出安全销的微观裂纹发生顺序和宏观断裂。基于疲劳寿命预测理论,对安全销的疲劳寿命和寿命使用系数进行了预测,计算表明安全销的疲劳寿命达到要求。

The ultimate load capacity of the 5A-ZM4 transmission tower is calculated. The controlling load of tower-line separation is determined based on the calculation result and the cross-section of safety pin as overload protection hardware is designed. The safety pin can make transmission line dissociate from tower when ice thickness exceeds the value corresponding to the uhimate load. The ultimate load capacity of safety pin is analyzed by nonlinear finite element method, which is consistent with the designed controlling load of tower-line separation. It was shown that the safety pin status changes from elasticity to plasticity gradually as the loads increase by analyzing safety pin load-displacement curve. The order of the microcosmic crack of safety pin and the macroscopic fracture are judged by the crack formation criteria and compared with the step loading analysis results. Based on fatigue life-span prediction theory, the fatigue life and the fatigue usage factors of safety pin are predicted in ANSYS. The analysis result showed that the fatigue life of safety pin could meet the requirement.