Harmonics are periodic distortions of voltage, current, or ability sine waves. Harmonics in power distribution programs will often be brought on by non-linear masses such as switched mode dc electric power materials and adjustable velocity motor drives.Theo nh? th?ng kê t? s? vé phát hành trong m?t ngày thì t? l? ?? th?ng ???c gi?i ??c ??c c?