ALTERNATOR

CONTENTS
SR.NO INDEX PAGE NO.
1 INTRODUCTION 1
2 CONSTRUCTION 3
3 PARTS 4
4 APPLICATIONS 5
5 MERITS/DEMERITS 6
What is an Alternator :
Construction, Working and Its
Applications
In 1832 Alternators are created by Hippolyta Pixii (1808-1835) the French
inventor. Some of the alternator manufacturer companies in India are Abrasive
Engineers Private Limited in Delhi, Accurion Scientific Instruments Private
Limited in Bangalore, Aditya Techno Private Limited in New Delhi, Agni Natural
Energy India Private Limited in Bangalore, Agragami Natures Electrical
Generating System Private Limited in Bangalore, Air Sensors Auto Electronics
Private Limited in New Delhi, Ajanta Switchgerars Private Limited in Pune, Alok
Electricals Private Limited in Uttar Pradesh, Ambica Elevator Private Limited in
Gujarat, Amico Engineers Private Limited in Kolkata, Anand and Co.electronics
Private Limited in West Bengal, Anand Technocrats Private Limited in
Maharashtra.
What is Alternator?
An alternator is defined as a machine or generator which produces AC (Alternating
Current) supply and it converts mechanical energy into electricalenergy, so it is
also called an AC generator or synchronous generator. There are different types of
alternators based on applications and design. The Marine type alternator,
Automotive type alternator, Diesel-electric locomotive types alternator, Brushless
type alternator, and Radio alternators are the types of alternators based on the
applications. The Salient Pole type and Cylindrical rotor type are the types of
alternators based on the design.
Construction of an Alternator
The main components of an alternator or synchronous generator are rotor and

stator. The main difference between rotor and stator is, the rotor is a rotating part
and stator is not a rotating component means it is a stationary part. The motors are
generally run by rotor and stator.
alternator-or-
synchronous-generator
The stator word based on the stationary and the rotor word based on the rotating.
The construction of the stator of an alternator is equal to the construction of the
stator of an induction motor. So induction motor construction and synchronous
motor construction are both are same. Thus the stator is the stationary part of the
rotor and the rotor is the component that rotates inside of the stator. The rotor is
located on the stator shaft and the series of the electromagnets arranged in a
cylinder causing the rotor to rotate and create a magnetic field. There are two types
of rotors they are shown in the below figure.
Salient Pole Rotor
The meaning of the salient is projecting outward, which means the poles of the
rotor are projecting outward from the center of the rotor. There is a field winding
on the rotor and for this field winding will use DC supply. When we pass the
current through this field winding N and S poles are created. The salient rotors are
unbalanced so the speeds are restricted. This type of rotorused in hydro stations and
diesel power stations. The salient pole rotor used for low-speed machines
approximately 120-400rpm.
Cylindrical Rotor
The cylindrical rotor is also known as a non-salient rotor or round rotor and this
rotor is used for high-speed machines approximately 1500-3000 rpm andthe
example for this is a thermal power plant. This rotor is made up of a steel radial
cylinder having the number of slots and in these slots, the field windingis placed
and these field windings are always connected in series. The advantages of this are
mechanically robust, flux distribution is uniform, operates at high speed and
produces low noise.
An AC motor comes in many shapes and sizes, but we can’t have an AC without a
rotor and stator. The rotor is made up of a cast iron and the stator is made up of
silicon steel. The prices of the rotor and stator depend on the quality.
Working Principle of Alternator

All the alternators work on the principle of electromagnetic induction. According
to this law, for producing the electricity we need a conductor, magnetic field and
mechanical energy. Every machine that rotates and reproduces Alternating Current.
To understand the working principle of the alternator, consider two opposite
magnetic poles north and south, and the flux is traveling between these two
magnetic poles. In the figure (a) rectangular coil is placed between the north and
south magnetic poles. Theposition of the coil is such that the coil is parallel to the
flux, so no flux is cutting and therefore no current is induced. So that the waveform
generatedin that position is Zero degrees.
rotation-of-rectangular-coil-between-two-magnetic-poles
If the rectangular coil rotates in a clockwise direction at an axis a and b, the

conductor side A and B comes in front of the south pole and C and D come in front
of a north pole as shown in figure (b). So, now we can say that the motion of the
conductor is perpendicular to the flux lines from N to S pole and the conductor cuts
the magnetic flux. At this position, the rate of flux cutting by the conductor is
maximum because the conductor and flux are perpendicular to each other and
therefore the current is induced in the conductor and this current will be in
maximum position.
The conductor rotates one more time at 900 in a clockwise direction then the
rectangular coil comes in the vertical position. Now the position of the conductor
and magnetic flux line is parallel to each other as shown in figure(c). In this figure,
no flux is cutting by the conductor and therefore no current is induced. In this
position, the waveform is reduced to zero degrees because the flux is not cutting.
In the second half cycle, the conductor is continued to rotate in a clockwise
direction for another 900. So here the rectangular coil comes to a horizontal
position in such a way that the conductor A and B comes in front of the northpole,
C and D come in front of the south pole as shown in the figure (d). Again the
current will flow through the conductor that is currently induced inthe conductor
A and B is from point B to A and in conductor C and D is from point D to C, so the
waveform produced in opposite direction, and reaches to the maximum value. Then
the direction of the current indicated as A, D, Cand B as shown in figure (d). If the
rectangular coil again rotates in another
900 then the coil reaches the same position from where the rotation is started.
Therefore, the current will again drop to zero.
In the complete cycle, the current in the conductor reaches the maximum and
reduces to zero and in the opposite direction, the conductor reaches themaximum
and again reaches zero. This cycle repeats again and again, dueto this repetition of
the cycle the current will be induced in the conductor continuously.
waveform-of-one-complete-cycle
This is the process of producing the current and EMF of a single-phase. Now for
producing 3 phases, the coils are placed at the displacement of 1200 each. So
the process of producing the current is the same as the single- phase but only the
difference is the displacement between three phases is 120 0. This is the working
principle of an alternator.
Characteristics
The characteristics of an alternator are
1. Output Current with Speed of Alternator: The output of the current

reduced or decreased when the alternator speed reduced ordecreased.
2. The efficiency with Speed of Alternator: Efficiency of an alternator is
reduced when the alternator runs with low speed.
3. Current Drop with Increasing Alternator Temperature: When the
temperature of an alternator increased the output current will bereduced or
decreased.
Applications
The applications of an alternator are
Applications
The applications of an alternator are
 Automobiles
 Electrical power generator plants
 Marine applications
 Diesel electrical multiple units
 Radiofrequency transmission
Advantages
The advantages of an alternator are
 Cheap
 Low weight
 Low maintenance
 Construction is simple
 Robust
 More compact
Disadvantages
The disadvantages of an alternator are
 Alternators need transformers

 Alternators will overheat if the current is high

ALTERNATOR

Uploaded by

Copyright:

Available Formats

ALTERNATOR

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

ALTERNATOR

Uploaded by

Copyright:

Available Formats

CONTENTS

SR.NO INDEX PAGE NO.

The main components of an alternator or synchronous generator are rotor and

Working Principle of Alternator

If the rectangular coil rotates in a clockwise direction at an axis a and b, the

1. Output Current with Speed of Alternator: The output of the current

 Alternators need transformers

You might also like