S? d?ng cho h? th?ng ?i?n h? th? khi ngu?n c?p ph? t?i b? gián ?o?n B? chuy?n m?ch t? ??ng, giám sát và chuy?n ??i gi?a hai ngu?n ?i?n Chuy?n m?ch three v? trí I - O - II- The ensured a gradual and stable breaking capacity whatever the running voltage by an open up operation employing a individual breaking spring.– T? ??ng kh?i ??ng ho?c d?n