Fundamentals of Electrical Engineering

Introduction

In late 1880's after Faraday published his laws of electromagnetic induction, first alternator was manufactured. The alternator by principle cannot produce a non-variable voltage with respect to time unlike a voltaic cell. Here the electrical technology was going through a great dilemma. On one hand, all electric appliances and instruments were manufactured for fixed voltage or DC voltage and on other hand, the demand of new generation or alternative voltages was in questions. The famous war of current between the father of DC voltages Thomas Edison and American engineer and manufacturer of AC voltage George Westing House was the most discussed issue in late 1880's. For a short span of time we used to use a commutator to get DC out of an alternator. It was very soon that there was a great revolution in electrical engineering as such and all equipments were redesigned and redeveloped to function in AC environment.

What is AC?

In a voltaic cell the output voltage does not vary with time. For a fixed load (i.e. for a constant current) the output voltage is constant throughout the time. In other words the voltage does not change its polarity. The voltage of this kind is the direct current voltage or DC voltage. The current is proportional to the voltage. So a DC voltage always feeds a constant unidirectional current to the circuit. Whereas, an AC voltage source changes its polarity and thus the current changes its direction accordingly. We get a variable bidirectional current from an AC source.