有關架空電纜的問題

1. made by steel wires; because high strength.
有那2個小原因為何會有這樣的轉變??
2. i don't understanding.
2 s' receive & transmit sensor on tower of each phase wire.
Ball on top for flight ; easy to look for safety.

OK?

其他答案更好。

架空電纜用銅鋁合金造，銅雖然導電好但重，全鋁很輕但導電差很多，其合金不重又導電不錯，適合長距螭電塔，132000伏特電壓令導電稍差也不是問題！