Harmonics are periodic distortions of voltage, recent, or electric power sine waves. Harmonics in ability distribution units will often be brought on by non-linear hundreds for instance switched method dc energy supplies and adjustable velocity motor drives.x? s? ki?n thi?t B? tr??ng Tài chính H? ??c Ph?c ch?t v?n casino Vân ??nHà N?i Ít ???c