Reducing harmonics with passive filters or active front-end drives?

Harmonics are caused by non-linear loads on the network, such as fluorescent lights, computers and AC drives. When adding further drives at a site, the total harmonic load must be considered. Most drives have six-pulse diode rectifiers, which give relatively high levels of total harmonic distortion, about 40 percent. Twelve-pulse rectifiers were introduced some years ago, which reduce total harmonic distortion to about 12 percent. However, in recent years, their place has been taken by…