8.1 INTRODUCTION

The modern electric utility industry began in the 1880s. On September 4, 1882, the first commercial power station, located on Pearl Street in lower Manhattan, known as Pearl Street electricity generating station went into operation providing light and electricity power to customers in a one square mile area. This was a DC power system built by Thomas Alva Edison, which was comprised of a steam driven DC generator connected through an electrical cable system at 110V and 59 customers spread over an approximate area with 1.5 km radius.

But now electrical energy is generated, transmitted and distributed exclusively in the form of alternating current (AC). The main drawback of DC generation is that it can neither be generated in bulk nor stepped up to higher levels for efficient transmission. Development of transformers changed the intact scenario of electrical power systems. Invention of induction motors (single phase and poly phase) by Nikola Tesla and the massive increase in load demand called for restructuring of the power systems. A majority of the loads in the present power system are inductive in nature, and whenever they are supplied from an AC source, they draw a current which is lagging by the applied voltage at an angle and immediately the power factor comes into picture.