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INDUCTORS, CAPACITORS
AND ALTERNATINGCURRENT CIRCUITS
MOHAMAD TARMIZI BIN ARBAIN
MECHANICAL DEPARTMENT OF POLITEKNIK PD
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INDUCTORS
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Basic principle of inductor
Inductors: electronic component that havingproperties to apposes the current changing
Inductance: electric circuit that having properties
to appose the current changing Induction: properties that opposes the current
changing
Unit: Henry (H)
1 Henry means total inductance in coil if thecurrent changing at rate 1 ampere second andproduce 1 volt of induces voltage
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2 types of induction
Self induction
When current flow through a coil, the current will change and fluxcutting also change. This changing will produce e.m.f in a coil. Thedirection of e.m.f is apposes the source voltage direction.
SYMBOL :-
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2 types of induction
Mutual induction
When alternate current flow through coil and flux was produces. Theflux will connected to the coil B which is situated next to the coil A.Hence, e.m.f will produce in coil B.
SYMBOL :-
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Self induction formula,L
Direction of e.m.f is reverse with direction of current
E.m.f generate cause of flux changing
E.m.f generate cause of current changing
Using Faradays Law
dt
dNe
1
dt
diLe
2
21 ee
dt
diL
dt
dN
di
dt
dt
dNL
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Thus, self induction ,L
L=Nd/di L= self inductionN= numbers of turns
d/dt= flux changing
dt/di= current changing
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Energy in inductor
To find the energy in the inductor use:
Unit : Joule (J)
2
2
1LIE
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Inductors in series circuit
LT= L1+L2+L3+L4
1/LT=1/L1+1/L2+1/L3
Inductors in parallel circuit
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Effect of inductor in curcuit
To smoothing effect on the wave form of the DC curcuit
To improve transmission characteristic of wave in phoneline
Inductive strain In alternate current circuit, current will change
continuously and induces reverse e.m.f continuously.
The e.m.f will oppose the current continuously. Theopposition to the current flow by inductance known asinductive strain.
fLXL 2
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CAPACITORS
A capacitor is an electrical device which have a functionto store electrical energy
A capacitor stores energy in the form of electric field thatis established by the opposite charges on the two plates
positives charges and negative charges
Current flow direction
V C
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Capacitor basic construction
A capacitor constructed of two parallel conductive platesseparated by an insulating material called the dielectric.
SYMBOL
C
UNIT
Farad (F)
Insulator
Conductor
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Capacitance
Capacitance is a property of capacitor to
charge /electrical energy
Or the amount of charge that a capacitor
can store per unit voltage across its plates
VQC
Q= charge (coulomb)
V= voltage (volt)
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Electrical energy in capacitors
To measure the energy in the capacitor
can use equation:
QVE2
1
Q= charge (coulomb)
V= voltage (volt)
2
2
1CVE
)(2
1 2
C
QE
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Types of capacitors
Variable dielectric air capacitors
Paper capacitors
Polyester capacitorsMica capacitors
Ceramic capacitors
Electrolytic capacitors Tantalum capacitors
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Function of capacitors
Increase electrical circuit power factor
Reduces firework when is on circuit
Reduces the interference of radio repeat inpendaflour circuit.
To firm electrical current
To store electrical charge
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Capacitive strain, XC
The opposition offered by a capacitor tothe flow of current through it:-
fCXC
21
C= capacitance (F)
F= frequency (Hz)
2= constant
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Capacitors in series circuit
CT= C1+C2+C3
1/CT=1/C1+1/C2+1/C3
Capacitors in parallel circuit
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ALTERNATING CURRENT
Alternating current was current flow in two condition in positive ornegative value.
It start from zero to maximum positive, back zero and then flow tomaximum negative and flow back to zero.
AC waveform similar to the sinus waveform like below diagram
Diagram AC waveform
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From diagram AC waveform, we can
generate the equation
V(t) = Moment Voltage (volt) Vm= Maximum Voltage/peak (volt)
t = Phase Angle change to time (rad/deg)
T = 2/(second)
tVtv m sin)(
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Term In AC Voltage
Vp(peak voltage) = maximum voltage in the diagram.
Vpp(peak to peak voltage) = measured from maximumpositive to maximum negative.
Va(average voltage) = the average value for sinuswaveform. Measured taken from the area under the ACsinus line. The value was 63.7% from maximum voltage.
Vrms(root means square voltage) = the important valuein electrical circuit. Most of meter show the reading inrms value (70.7%) from the peak voltage in AC.
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Diagram AC waveform with AC term position
I cycle = 3600 = 2rad
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In phase waveform Wave A and wave B was in phase waveform because start and end
at same time. But both of it have difference maximum voltage.
tVtv p sin)( 1
tVtvp
sin)(2
A :
B :
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Out Of Phase Waveform In this case, e.m.f value in all waveform were same (Vp) but reach at maximum value
or zero value at different time.
Then it have different phase Each of waveform has difference in phase angle (and ).
Wave through zero point (0o) taken as references.
1. Wave B was references for all wave.
2. Wave A leads wave B with .
3. Wave C lags wave B with .
tVtv p sin)(
)sin()( tVtv p
)sin()( tVtv p
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Purely resistance (R)
For basic circuit use AC as poser supply, the current that flow in that circuitcan be determine by using Ohm Law
In AC resistance circuit, current and voltage in phase because no anglemovement.
Effect of resistance in the AC circuit If the resistance higher, current flow will decrease
If the resistance lower, the current flow will increase. Pure resistance will not effected the frequency of the circuit
Pure resistance circuit Pure resistance waveform Pure resistance vector
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Purely induction (L) When electric flow in the induction winding, this will become electromagnet
which will produce resistance voltage to oppose current flow.
This resistance to the current electric flow in the winding known as inductivestrain, XL.
In AC circuit if consist of induction, current will lags the volt with differentphase in 90o
The effect induction in the AC circuit
The oppose to the current work known as inductive strain and in valuesame as resistance.
Inductive strain was dependant to the frequency. Increase frequency willincrease voltage and also increase resistance.
Pure induction circuit Pure induction waveform Pure induction vector
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Purely capacitance (C)
in AC circuit consist of capacitor, current will leads of voltage in 90o. Effect of capacitor in AC circuit
Opposes to current known as capacitive strain.
Value same to the resistor resistance.
It dependent to frequency value. Which increasing frequency source,thus the capacitive strain will increase.
Pure capacitance circuit Pure capacitance waveform Pure capacitance vector
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Impedance triangle RL
Impedance define as the sum of resistance appear in ACcircuit.(symbol=Z, unit=)
It can be represent in triangle diagram to connected eachcomponent known as impedance triangle.
By using Theorem Pythagoras can be created from impedancetriangle
Impedance triangle RL diagram
fLXXRZ LL 2,22
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Current and voltage in RL series circuit.
Circuit current =
Drop voltage each component
and
Phase angle
Power factor,
ZVI
)(tan 1
R
XL
Z
Rcos
IRVR LL IXV
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RC circuit Resistance and capacitor in series connection
In the series circuit, current value same to every load. Thencurrent (I) become the reference factor.
From the figure, current will be limited by resistance ,R andcapacitive strain,XC.
This make current flow in the resistance in phase with voltage
But when current through inductive strain XLit will leads in 90o
RC series circuit RC vector diagram
22
CR VVV
IRVR
CC IXV
Resistance
voltage
Capacitive strain
voltage
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Capacitance triangle RC
From vector diagram, it can created triangleimpedance.
By using Theorem Pythagoras, capacitanceimpedance equation was
Capacitance triangle RC diagram
22CXRZ
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RLC circuit
Inductor (L), Capacitor (C) and Resistor (R) connected in seriesorder and connected to AC power supply (V).
Current (I) subjected as reference factor in vector diagram
RLC series circuit
Before draw RLC vector diagram, two (2) condition need to be define
a) Inductive strain grater then capacitive strain. (XL>XC)
b) Capacitive strain grater than inductive strain. (XC> XL)
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a)Inductive strain grater then capacitive
strain. (XL>XC)
a) Impedance circuit,
b) Current circuit
c) Drop voltage each component
d) Phase angle
e) Power factor
22)( CL XXRZ
Z
V
I
,IRVR andIXV CC LL IXV
)(tan 1
R
XX CL
Z
Rcos
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The equationsame as
previous but
change at
phase angle
(-)
)(tan 1
R
XX CL
b) Capacitive strain grater than inductive
strain. (XC> XL)
a) Impedance circuit,
b) Current circuit
c) Drop voltage each component
d) Phase angle
e) Power factor
22)( CL XXRZ
Z
V
I
,IRVR andIXV CC LL IXV
Z
Rcos
The equation
Same as previous
But change at
Phase angle (-)
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Power factor
Power factor can be phrase in percentage (%) or infraction.
Known as and rephrase as lead or lag.
is angle phase angle between voltage and current Power factor also ratio between true power to apparent
power.
Also define as ratio resistance to impedance.
Lead power factor is current lead the voltage whenvoltage taken as reference factor with +tive value.
Lag power factor is current follow voltage when voltagetaken as reference factor withtive value.
Good power factor when it value is 1.
Cos
S
PCos
Z
RCos
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Power in AC circuit
There are 3 power in AC circuit:1. Apparent power, S.
2. Active power, P.
3. Reactive power.
Apparent power, S was lost power because of resistance to make current
and voltage separate or out of phase.
Apparent power, s
Symbol : S
Unit : voltage- Ampere (VA)
Apparent power = voltage x currentVIS
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Also known as active power. Define as power use or absorb by the resistance
component in AC circuit
True power, P
Symbol : P
Unit : Watt (W)
Apparent power = voltage x current x power factor
Strain power, QAlso known as reactive power. Define as power use or absorb by the capacitor
component or inductor component in AC circuit
Symbol : Q
Unit : Voltage Ampere Strain (VAR)
Apparent power = voltage x current x sin
cosVIP
sinVIQ
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