Harmonics are periodic distortions of voltage, current, or energy sine waves. Harmonics in electric power distribution techniques will often be because of non-linear masses for instance switched method dc power materials and adjustable pace motor drives.Bi-a VN th?ng ngo?n m?c tuy?n B? có "Th?n c?", t?o m?c l?ch s? gi?i ??ng ??i th? gi?i (Tin th?