Harmonics are periodic distortions of voltage, latest, or power sine waves. Harmonics in electricity distribution systems are sometimes caused by non-linear loads like switched manner dc energy supplies and adjustable pace 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?a x? s? ki?n thi?