CHARGING
SYSTEM
Introduction:
This
system is necessary in Automobiles, where the storage battery is the main
source of electricity. By this system, the electricity is replaced in to the
battery after being used in starting system, lighting system and etc.
Usually,
the Automobile generators are low voltage D. C generators producing direct
current, because the use of battery requires direct current. In recent years,
alternator type generators are also used. The alternator employs Diodes to
convert the generated alternating current
into direct current.
WORKING PRINCIPLE OF D. C . GENERATOR:
When a conductor is moved in a magnetic field, a current is produced in it. The direction of flow of current is determined by Fleming’s left hand rule. It gives relationship between the direction of lines of force direction of conductor motion and direction of current flow.
Construction and working of D C Generator:
Mostly
Commentator type D C Generators are used in Automobiles. It consists of pole
pieces fitted in a frame armature commutator and filed winding. The pole s hoes
are the laminated iron cores for the filed winding that furnish the magnetic
field for the generator. Most generators contain one pair of Nort-South poles,
shaped to allow the armature to rotate
between
them with little clearance. The armature is made up of conductors of insulated
wire around on a laminated iron core. The conductor ends are soldered to copper
tars, separated from each other by mica which make the commutator. A steel
shaft running the armature
and
commutator is supported by means of bearing so that the pulley and fan mounted
on the front end can be turned by an engine driven belt. Two carbon brushes are
held in the brush holders, which make firm contact with commutator segments in
order to connect the coils of
rotating
armature with the outside circuit.
Working: When the armature rotates, the current is induced and flows in the conductors through the load. Part of the current flow through the two-field winding assemble around two magnetic poles. The magnetic field is strengthened. The Armature and commutator are designed to rot
AUTO TRANSMISSION SYSTEM ate together. They allow the generator to produce e a flow of direct current continues to flow in the same direction.
Cutout:
The Cut-out
relay (or Circuit breaks) is an automatic device between dynamic and the
battery which prevents the battery from discharging through the dynamo, when
dynamo is not charging the battery. It is a magnetic switch and consists of two
windings shunt winding
and series winding. Closes the circuit between the generator and the battery when the generator is producing current.
Voltage Regulator:
The Voltage regulator consists of a relay coil wound with many turns of fine wire on the Iron core. The function of voltage regulator is to control the magnetic field circuit of dynamo. It consists of two windings on a single core, a shunt winding of many turns of fine wire and series winding
of a few turns of heavy wire. The Shunt winding (Voltage winding) is connected at the input side of the cut out and grounded to the other end. The series or current winding is connected at one end to the filed circuit of the generator and at the other end to the contact point of armature.
Current Regulator:
It consists of electromagnet coil of heavy wire design to carry the full current. Electromagnet controls a pair of contacts. When the contacts are closed and the dynamo speed is more, an increasing current flow through the coil of the electromagnet. When the current is too high, themagnetic pull will overcome the tension of the spring and the contacts are separated. When the contacts open, the filed current is reduced causing reduction of out. When the current is less the electromagnet pull is reduced and again the contacts close.