Harmonics are periodic distortions of voltage, current, or electrical power sine waves. Harmonics in power distribution units tend to be due to non-linear hundreds including switched method dc electric power provides 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? ???