Harmonics are periodic distortions of voltage, current, or power sine waves. Harmonics in power distribution systems will often be due to non-linear masses including switched method dc electrical power supplies and adjustable velocity motor drives.Th? thao Mourinho nh?n ???c l?i m?i h?p d?n v? làm th?y Fred ??i bóng danh ti?ng Th? Nh? K? - Fenerb