我wo們men單dan位wei跟gen換huan變bian壓ya器qi的de時shi候hou我wo用yong相xiang序xu儀yi,為wei的de是shi防fang止zhi變bian壓ya器qi換huan完wan以yi後hou設she備bei的de電dian機ji轉zhuan向xiang出chu差cha錯cuo,我wo的de是shi三san根gen表biao筆bi分fen別bie與yu三san相xiang電dian源yuan接jie觸chu,表biao上shang的de燈deng顯xian示shi正zheng向xiang或huo者zhe逆ni向xiang,還hai可ke以yi通tong過guo互hu感gan器qi測ce高gao壓ya的de。