ABSTRACT
This chapter introduces the various indices of power quality. Power quality refers to the sudden deviation in voltage, current, or frequency that result in equipment mis-operation. Power quality indices or issues are classified based on their intensity and nature in making the system unstable. Examples of power quality indices include sag, swell, voltage imbalance, transients, voltage fluctuations, harmonics, noise, etc. The standards associated and equations involved with these indices are addressed in detail. Principles of overvoltage protection and devices involved for overvoltage protection are explained. The origins of short interruptions and their monitoring were analyzed with illustrations.
