Harmonics are periodic distortions of voltage, existing, or ability sine waves. Harmonics in energy distribution devices in many cases are a result of non-linear masses like switched method dc electricity supplies and adjustable pace motor drives.V?i nhi?u s? ti?n ích, m?i l? và ??c ?áo trong ch?t l??ng d?ch v?. 123B hy v?ng ng??i ch?i s? ???c t