Harmonics are periodic distortions of voltage, current, or electricity sine waves. Harmonics in power distribution systems are frequently due to non-linear hundreds for instance switched manner dc electricity supplies and adjustable pace motor drives...M?i câu l?c b? t?i Ngo?i h?ng Anh khi ra sân ??u là nh?ng ng?n l?a b?c cháy v?i tinh th?n thi