超高压双回路线路由于电气间隙大、绝缘子串长，换位时跳线布置方式复杂。双回路三柱组合换位耐张塔在2基主塔之间布置辅塔，利用辅塔跳线内绕进行跳线的上下交换，实现线路换位。采用这种换位方式的跳线接线简洁明了，设计、施工、运行都较为方便，总体性能更加安全可靠。三柱组合换位耐张塔通过分塔挂线、取消导线横担、优化跳线布置方案等手段，有效降低了塔高，减小了塔身尺寸，改善了铁塔受力，提高了结构可靠度，与常规双回路换位塔相比，三柱组合换位耐张塔塔重指标降低了23.4%。

The jumper arrangement in UHV double-circuit transmission lines is more complex, because of the bigger electrical clearance and longer insulator string. By arranging auxiliary tower between two main towers, and rounding the soft jumper from tower inside, jumper exchanged from top to bottom to realize the line transposition in three-pole-composite transposition strain tower. This jumper connecting is simple and clear, which makes the design, construction and operation more convenient, and also makes the overall performance more safety and reliable. The method of separating line-hanging, canceling tower cross arm and optimizing the jumper layout can effectively reduce the size and height, ameliorate the endured force, and improve the structural reliabilities of three-pole-composite strain tower. The weight of three-pole-composite transposition strain tower decreases by 23.4% than that of normal double-circuit transposition tower.