Harmonics are periodic distortions of voltage, latest, or electricity sine waves. Harmonics in electric power distribution programs will often be a result of non-linear masses such as switched method dc ability provides and adjustable velocity motor drives. trong m?t kho?n th?i gian nh?t ??nh tr??c khi ?i?u ch?nh, t?t nh?t b?n nên dùng ph??ng ph