Topic :
capacitor
Prepared by :
Ashwini R. Binnar
Guided by Mr. Lullhe
Introduction
Defination of capacitor:
Capacitor displays its true
characteristics only when a
change in voltage is made in the
network.
To store the electric charge
per unit volume it is called
What is purpose of
capacitor
The main function of
capacitor are
To Store electricity or
energy & also
To supply required reactive
power
To improve power factor of
Capacitors
A basic capacitor has two parallel
plates separated by an insulating
material
A capacitor stores an electrical charge
between the two plates
The unit of capacitance is Farads (F)
Capacitance values are normally
smaller, such as F, nF or pF
Capacitance
The relationship between
voltage difference and charge
is normally linear
This allows us to define
capacitance
Capacitance has units of
Coulomb/Volt
Farad,
Q Also known as a
C
C
abbreviated
FF V
V
Q C V
A Farad is a very large
amount of capacitance
Capacitors in Parallel
When capacitors are joined at
V
both ends like this, they are
said to be in parallel
They have the same
voltage across them Q1 C1V
They can be treated like a Q C V
2
2
single capacitor:
C1
Q C V
C2
C C1 C2
Q Q1 Q2 C1 C2 V
Capacitors in Series
When capacitors are joined at
Q C1V1
V
one end, with nothing else,
C
Q C2 V2
they are said to be in series
1
C
They have the same
2
Q
Q
voltage across them V V1 V2
Q
They can be treated like a
C1 C2 C 1 1 1
C C1 C2
single capacitor
Capacitors
Storing a charge
between the plates
Electrons on the left plate
are attracted toward the
positive terminal of the
voltage source
+
+
_
_
This leaves an excess of
positively charged holes
The electrons are pushed
toward the right plate
Excess electrons leave a
negative charge
Energy density in a
capacitor
Energy density is energy
over volume
U 12 C V
A
2
u E
1
2 0
We can associate the energy with
the electric field itself
This formula can be shown to be
completely generalizable
It has nothing in particular to do
with capacitors
Capacitors
Types of Capacitors
_ Fixed mica, ceramic,
electrolytic, tantalum and
polyester-film
Tantalum
capacitor
Aluminum
electrolytic
capacitor
Sliver mica
capacitor
Different types of
capacitor
Ac motor
capacitor
Water
pump
capacitor
Motor run
capacitor
Electrolytic capacitor
Some capacitors
are polarised, they
can only be
connected one
way around
Electrolytic
capacitors are
polarised
Used as to stored
Variable Capacitors
Variable capacitors are
used in communication
equipment, radios,
televisions and VCRs
They can be adjusted by
consumers by tuning
controls
Trimmers are internal
adjusted capacitors
that a consumer cannot
adjust
Used to radio tunning
Capacitors
Polyester-film Capacitors
_ The capacitor can be used for
both dc and ac networks.
Metalized polyester film capacitor
(MPE)
Capacitors
Ceramic Capacitors
_ Made in different shapes and sizes but
the basic construction is the same
_ Ceramic capacitors have very low leakage
current and can be used in both dc and ac
networks.
Different type of ceramic
Applications
_ Capacitors find applications in:
_ Electronic flash lamps for cameras
_ Line conditioners
_ Timing circuits
_ Electronic power supplies
_ Transmission line
Thank's...
