Working Principle of AC Generator!
Summary
TLDRThis YouTube video delves into the workings of an AC generator, an electric machine that transforms mechanical energy into alternating electrical currents through electromagnetic induction. It outlines the core components like the armature, shaft, field magnets, slip rings, brushes, and galvanometer. The video explains how the armature's rotation within a magnetic field induces a current, and Fleming's right-hand rule determines its direction. It also illustrates the sinusoidal pattern of the induced EMF over time, showcasing the generator's alternating current production. The host encourages viewers to subscribe and support their Patreon for more informative content.
Takeaways
- π AC generators convert mechanical energy into electrical energy in the form of alternating current (AC).
- 𧲠The principle of operation is based on electromagnetic induction, where relative motion between a coil and a magnetic field induces current.
- ποΈ The armature is a key component that carries current and consists of many wire coils, converting electrical power to mechanical power.
- π The shaft is the moving part that connects the armature and transfers torque.
- 𧲠Field magnets have two poles (north and south) and produce a radial magnetic field.
- π Slip rings are conductive and rotate with the armature, transferring power to and from the rotor.
- βοΈ Brushes are in contact with the rotating slip rings and connect to the external circuit.
- π A galvanometer is used to show the flow of current in the external circuit.
- π The direction of the induced current changes with every half rotation of the armature.
- π The induced electromotive force (e-m-f) varies over time, forming a sinusoidal wave.
Q & A
What is an AC generator?
-An AC generator is an electric machine that converts mechanical energy into electrical energy in the form of alternating electromotive force or alternating currents.
On what principle does an AC generator operate?
-An AC generator operates on the principle of electromagnetic induction.
What is the role of the armature in an AC generator?
-The armature is a part of an AC generator that carries a current and consists of many coils of wire. It converts electrical power to mechanical power in the form of torque and transfers it via the shaft.
What is the function of the shaft in an AC generator?
-The shaft is the moving part of the generator and is connected to the armature. It transfers the mechanical power in the form of torque.
What are the characteristics of the field magnets in an AC generator?
-Field magnets in an AC generator consist of two poles, north and south, and are concave and cylindrical in shape, producing a radial magnetic field with the direction from north to south pole.
What is the purpose of slip rings in an AC generator?
-Slip rings are connected to the armature and rotate with it. They are made of a circular conducting material and are used to bridge, transfer, and carry the power to and from the rotor of an AC generator.
What are brushes and how are they connected in an AC generator?
-Brushes, usually made of carbon, have one end in contact with the rotating slip rings and the other end connected to the external circuit. They facilitate the flow of current from the rotating part to the stationary part of the generator.
What is the purpose of a galvanometer in an AC generator?
-A galvanometer is connected to the external circuit to show the flow of current. It provides a visual indication of the alternating current passing through it.
How does the direction of induced current change as the armature rotates?
-The induced current changes direction for every half rotation of the armature. This is due to the relative motion between the armature and the magnetic field, which induces current in opposite directions during each half rotation.
How does the induced electromotive force (EMF) change over time during one full rotation of the armature?
-The induced EMF changes sinusoidally over time, increasing to a maximum value, then decreasing back to zero, reversing polarity, and returning to zero again, completing one cycle during one full rotation of the armature.
What is the significance of the sinusoidal representation of induced EMF in an AC generator?
-The sinusoidal representation of induced EMF indicates that the current is alternating, which is the fundamental characteristic of AC or alternating current. This waveform is crucial for understanding the behavior of AC power in electrical systems.
Outlines
π Understanding the AC Generator
The script introduces an AC generator, an electric machine that transforms mechanical energy into electrical energy through alternating electromotive force (EMF) or currents. It operates on the principle of electromagnetic induction, where relative motion between a coil and a magnetic field induces an electric current. The components of an AC generator are explained, including the armature, which is responsible for carrying current and converting electrical power into mechanical power via torque. The shaft, field magnets, slip rings, brushes, and galvanometer are also described, each playing a role in the functioning of the generator. The working principle is further detailed, explaining how the armature cuts magnetic field lines to induce current and how this current flows through the connected circuits. The direction of induced current is discussed using Fleming's right-hand rule, and the script describes the change in current direction with each half rotation of the armature.
π AC Generator's EMF Over Time
This section of the script delves into how the induced EMF in an AC generator changes over time. It describes a graphical representation of the EMF, assuming the armature completes a full rotation in T seconds. The script explains that at the start, with the armature in a vertical position, the rate of change of magnetic flux is zero, resulting in zero induced EMF. As the armature rotates through the first quarter, the EMF increases to a maximum value when the armature is horizontal. During the second quarter, the EMF decreases back to zero. The third and fourth quarters mirror this pattern but with opposite polarity. The script concludes by noting that the induced current's direction changes with each half rotation, and the graphical representation shows a sinusoidal wave form, typical of alternating current (AC).
Mindmap
Keywords
π‘AC generator
π‘Electromagnetic induction
π‘Armature
π‘Shaft
π‘Field magnets
π‘Slip rings
π‘Brushes
π‘Galvanometer
π‘Fleming's right-hand rule
π‘Induced EMF
π‘Alternating current (AC)
Highlights
AC generator converts mechanical energy to electrical energy in the form of alternating current.
AC generator operates on the principle of electromagnetic induction.
Armature is the part of an AC generator that carries current and consists of many wire coils.
The armature converts electrical power to mechanical power in the form of torque.
The shaft is the moving part of the generator, connected to the armature.
Field magnets consist of two poles, north and south, producing a radial magnetic field.
Slip rings are connected to the armature and rotate with it, transferring power to and from the rotor.
Brushes are in contact with the rotating slip rings and are connected to the external circuit.
A galvanometer is used to show the flow of current in the external circuit.
When the armature rotates, it cuts the magnetic field lines, inducing current in the coil.
The induced current flows through the armature, slip rings, brushes, and galvanometer.
The direction of induced current can be determined using Fleming's right-hand rule.
Induced current changes direction with every half rotation of the armature.
The induced e-m-f changes over time, represented graphically as a sinusoidal wave.
At the start of rotation, the rate of change of magnetic flux is zero, resulting in zero induced EMF.
During the first quarter rotation, the induced EMF increases from zero to a maximum value.
At the midpoint of rotation, the rate of change of magnetic flux is at its maximum, and so is the induced EMF.
During the second quarter rotation, the induced EMF decreases from its maximum to zero.
In the third quarter rotation, the induced EMF increases from zero to a maximum negative value.
In the last quarter rotation, the induced EMF decreases from its maximum negative value to zero.
The graphical representation shows how induced current changes over time in a sinusoidal pattern.
Transcripts
[Music]
hi and welcome back to my youtube
channel in this video we will talk about
the AC generator AC generator is an
electric machine that converts
mechanical energy to electrical energy
in the form of an alternating
electromotive force or alternating
currents AC generator works on the
principle of electromagnetic induction
so when we have relative motion between
a coil and a magnetic field an electric
current or electro-motive force is
induced in the coil let's look at the
basic components of AC generator
armature is part of an AC generator
which carries a current and consists of
many coils of wire armature converts
electrical power to mechanical power in
the form of torque and transfers it via
the shaft shaft is movement part and
it's connected to armature field magnets
consists of two poles north and south
pole field magnets are concave and a
cylindrical shape and therefore produce
radial magnetic field direction of the
magnetic field is from north to south
pole
slip rings s1 and s2 are connected to
the armature and rotates together with
it the slip ring consists of a circular
conducting material that is connected to
the armature rotor windings slip rings
are used to bridge transfer and carry
the power to and from the rotor of an AC
generator brushes b1 and b2 are usually
made of carbon one end of each brush is
in contact with rotating slippering and
the other end is connected to the other
circuit
Calvino meter is connected to outer
circuit purpose of galvanometer is to
show the flow of current in the external
circuit furthermore we will explain the
working principle of the AC generator
when the armature rotates between the
poles of magnetic field armature cuts
the lines of magnetic field and
generates current in the coil of
armature this induced current then flows
through the circuits connected to the
armature in fact it flows through the
armature slip rings brushes and through
galvanometer in which we have a response
as you can see galvanometer needle
swings between negative and positive
values
this means that alternating current
passes through galvanometer
when current is induced in the armature
it's necessary to know the direction of
that induced currents so initially
armature coil ABCD is in a vertical
position armature part a B is up while
Part C D is down as you already know
direction of the magnetic field is from
north to south pole
undergo half rotation in clockwise
direction part of armature a B goes down
while Part C D goes up
according to Fleming's right-hand rule
the thumb indicates the direction of
movements of the armature part C D it is
in fact direction of the force which is
upwards first finger points direction of
magnetic field from north to south pole
and second finger shows direction of
induced currents in our case current
will flow in direction D CBA of armature
and from brush b1 to brush b2 through
galvanometer
if we take another half rotation parts
of armature a B moves up while Part C D
moves down again according to Fleming's
right-hand rule the thumb indicates the
direction of movements of the armature
part C D it is in fact direction of the
force which is downwards first finger
points direction of magnetic field from
north to south pole and the second
finger shows direction of induced
current in our case currents will flow
in Direction ABCD of armature and from
brush B to to brush b1 through
galvanometer
to conclude induced currents changes
direction for every half rotation
next thing we need to see is how induced
e-m-f changes over time to see this
graphically representation of induced
e-m-f we have to assume that armature
needs T seconds to complete full
rotation in time T equals zero seconds
armature ABCD is in a vertical position
part of armature a B is up and Part C D
is down part of armature a B and Part C
D moves parallel to the magnetic field
at that moment also at that moment the
rate of change of magnetic flux is zero
therefore induced EMF is zero
for the first quarter rotation from T
equals zero seconds to T over four
seconds part of armature a B moves down
and Part C D moves up in this period
induced EMF increases from zero to
maximum value in T over four seconds
armature is in horizontal position in
relation to the magnetic field in T over
four seconds rate of change of magnetic
flux momentarily gain maximum value
therefore the induced EMF at disposition
is maximum
cheering second quarter of rotation from
t over for second 2t over two seconds
part of our mature AP moves again down
and Part C D moves up in this period
induced e-m-f decrease from its maximum
value to zero in T over two seconds
armature again is in vertical position
part of armature a B is down and Part C
D is up part of armature a B and Part C
D moves parallel to the magnetic field
at that moment also at that moment the
rate of change of magnetic flux is zero
therefore induced EMF is zero
during the third quarter of rotation
from T over two seconds to three T over
four seconds part of armature a B goes
up and Part C D moves down in this
period induced EMF increases from zero
to maximum value but in this period
induced EMF has opposite polarity in
three t over four seconds rate of change
of magnetic flux momentarily gain
maximum value but compared to a position
in T over four seconds induced EMF
gained it's negative value
finally during the last quarter of
rotation from 3 T over 4 seconds to T
seconds part of our mature AP goes up
part C D moves down in this period
induced e-m-f decreases from its maximum
negative value to 0 in time T seconds
armature is in a vertical position again
armature is moving parallel with
magnetic field rate of change of
magnetic flux is zero therefore induced
EMF is zero
from this graphically representation we
saw how induced current changes in time
as you probably already know the term AC
or alternating current generally refers
to a time varying wave form or sinusoid
and we saw that sinusoid in this
graphical representation
I hope that through this video you
gained new knowledge about AC generators
don't forget to subscribe like and share
this video watch the rest of my videos
from my youtube channel please consider
to support me on patreon
thanks very much see you on the next
video
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