System Problems and Electronic Loads: Harmonics, Resonance and Commutation

With the increased use of electronic loads such as variable frequency drives (VFD) and uninterruptible power supplies (UPS), power quality problems are becoming more common. These power quality problems can be difficult to identify and can be even more difficult to correct. Acceptable power is more than just a good rms voltage; it is a signal with a defined strength and shape. Power quality problems are distortions of that shape.