How electricity is generated

5 How electricity is generated

5.1 Direct Current Generator

A generator is a machine that converts mechanical energy into electrical energy. A direct current generator, thus, converts mechanical energy into electrical energy. It produces two electrical components:
(a) Direct voltage.
(b) Direct current.
A direct voltage is that which does not reverse direction. It can be represented by a continuous line above a certain point (reference point). This direct voltage is either positive or negative.

dc generator voltage vs reference point

A direct voltage can be steady if is constant with respect to time or it may be term unsteady if it fluctuates with respect to time as shown below:

dc voltage vs time

All the above voltages are direct voltage because they are all positive with respect to y=0 axis when drawn from the origin.
Like the direct voltage, direct current is also represented similarly as shown below.

dc generator current vs reference point

Steady and unsteady current is represented below:

dc voltage vs time