Harmonics are periodic distortions of voltage, present, or energy sine waves. Harmonics in ability distribution units are sometimes due to non-linear loads including switched method dc ability materials and adjustable speed motor drives.M Xu?t b?n Kinh doanh Công ngh? ??i s?ng Tác gi? S?c kh?e Gi?i trí Th? thao Th? gi?i sách Du l?ch Way of life