Page 235 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Purpose of Charging System
Various assistive devices requiring electricity in fuel engine based vehicles
Charging system is very necessary for operation, because with its help it becomes possible to supply electricity
to these devices. Almost all of these devices are battery operated. We know very well that the battery needs
constant charging, because it keeps getting discharged during its continuous use. Electrically based devices run
smoothly for many years with the help of batteries. Alternator is used to charge the battery. The current from the
battery is used to start the engine, blow the horn, turn on the lights and run all other devices. Therefore, providing
continuous charge to the battery is the priority of the charging system.
Components of Charging System The components which are required to maintain the level of charge in the
charging system for regulation of power supply are called components of the charging system. The main
components of charging system are as follows
1 Alternator 2 Battery 3 Rectifier assembly 4 Indicator 5 regulator

Importance of voltage Regulation

Objectives: At the end of this lesson you shall be able to
• explain the importance of voltage regulation.

The voltage regulation of an alternator: The voltage regulation of an alternator is defined as the rise in voltage
when the load is reduced from the full rated value to zero, with the speed and field current remaining constant. It
is normally expressed as a percentage of the full load voltage.
V - V
% of voltage regulation = NL FL x 100
V FL
where V - no load voltage of the alternator
NL
V - full load voltage of the alternator
FL
The percentage regulation varies considerably, depending on the power factor of the load, and as we have seen
for leading P.F. the terminal voltage increases with load, and for lagging P.F. the terminal voltage falls with the
load.
Example: When the load is removed from an AC generator, its terminal voltage rises from 480V at full load to
660V at no load. Calculate the voltage regulation.
V - V
% regulation = NL FL x 100
V FL
660 - 480
x 100 = 37.5%
480

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CITS : Automotive - Mechanic Diesel - Lesson 67 - 70