There are three main types of harmonic sources: ① rectifiers, inverters, switching power supplies, static converters, thyristor systems and other SCR control systems and other power electronic equipment, ② transformers, motors, generators and other non-linear equipment, ③ electric arc furnace equipment and gas electric light source equipment.
Professional equipment can be used to monitor harmonics, such as SF DZ-3 power quality monitor, SF DZ-4 power quality analyzer.