Improperly distributed power and poor power quality can cause costly energy charges and cause damage to valuable electronic and electrical equipment.  Proper management of power will protect electrical devices from malfunction, premature or permanent failure and ensure the efficient use of one of the most costly assets.
Poor power quality can be generated by a multitude of causes.  
Power Quality is characterized by:
—Stable AC voltages at near nominal values and at near rated frequency subject to acceptable minor variations, free from annoying voltage flicker, voltage sags, frequency fluctuations.
—Near sinusoidal current  and voltage wave forms free from higher order harmonics.
All electrical equipment are rated to operate at near rated voltage and rated frequency. Hence Power Quality Analysis is one of the criteria of for assessing the power quality.