Power quality is an increasingly important topic in design of modern buildings. They are filled with sophisticated electronic equipment that demand an adequate supply of electricity: free of noise, sags, surges, and other “dirty” power phenomena. In short, quality is becoming as important as quantity.
The extent of variation from this ideal voltage source that can be tolerated, depending on the duration of the event and disturbances, are often classified by how much and for how long the voltage deviates from an ideal sine wave. In general, the shorter the duration, the greater the magnitude of deviation that can be tolerated (Figure 2).