Harmonics are periodic distortions of voltage, existing, or electricity sine waves. Harmonics in energy distribution devices are sometimes brought on by non-linear masses for example switched mode dc energy supplies and adjustable velocity motor drives.?i?u này là thi?t thòi l?n cho các V?V ??nh cao trong b?i c?nh ph?i t?p luy?n, thi ??u, c?nh