Basic Electrik

8/6/2019 Basic Electrik

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Basic

Electricity


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MaterialMaterial

Substance Element Atom

Fundamental of material


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Occurrence of electricityOccurrence of electricity

Material Molecule Atom Atomic nucleus Nucleus

Proton

Electron

What is electricity?


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Occurrence of electricityOccurrence of electricity

Electron Nucleus

Shell

Electrons

Protons

Neutron

++

+

-

Electrons

Structure of Atom Detail str ucture of Atom

Structure of Atom


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Occurrence of electricityOccurrence of electricityAtom ionpositive ion

Negative ion

Electrically Neutral

Positive Ion Negative Ion


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Occurrence of electricityOccurrence of electricityFree Electron Movement = Occurrence of electricity

+++

--

-

-

--

--

-

-

Fundamental question


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Current, Voltage, ResistanceCurrent, Voltage, Resistance

Current

Voltage

Resistance


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Current 1Current 1

Water tank A

(Positive terminal)

Water tank B

(Negative terminal)

Current

flow

Water level

difference

(Potential

difference)

Water

wheelrotate

Lamp

ON

Flowing of current is transfer of free electron .

When there is electrical potential

Current flow .

Electrical energy : Transfer

Amount of free electron .

If transfer track of free electron

Grows, big current passes .

If quantity of current big

Actuator's drive increase .


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Current 2Current 2

Tank A Tank B

Same waterlevel

No potential

Difference

No current

flow

No water

wheel

Rotate

Lamp

OFF

It is no stream of current that it is no transfer of free electron .

When there is no electrical

Potential, current not flow .

Electrical energy : Because it is no

Transfer of free electron, there is

no

Occurrence of energy

Because current does not flow

There is no actuator drive .

Because there is no electrical

Potential, cu

rrent does not flow .


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Current 2Current 2Current represent

The ampere is expressed using the letter I .

The ampere describes the rate of flow of electrons past any given point

In a circuit .

Current unit : A (Ampere)

1 Ampere : One ampere is equal to one coulomb of

Charge flowing Part a point in one second .

I = Q/T (Q : Coulomb, T : Second)

1 coulomb = 1/1.6012910-9 = 6.251018

Thus, The electric charge amount that pass per time

1 A : 1,000, 1 : 0.001 A, 1 : 1,000 A


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Potential and potential difference VS .Potential and potential difference VS .

CurrentCurrent

Water tank B

Low water level

Water current

Water tank A

High water level

Water level

Difference

(Potential

Difference)

Water wheel : ON

Water wheel work

Water Flow

No water current

Water tank A Water tank B

No water level

Difference(Potential same)

Water wheel : OFF

Water wheel does not work

No Water Flow

Current flowing


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Current FunctionCurrent Function3 function of current.

Heat function

Ex) cigar lighter, electric stove etc

Magnetism function

Ex) solenoid

Chemistry functionEx) battery


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Summary for currentSummary for current Flowing of current is transfer of electron .

If transfer of electron is much, mean that current passes much .

Though there is potential difference, current passes

When connected between high and low potential .

If transfer of free electron is much, heat generate

Therefore, electric wire bunt out that is done

Because so much current passed .

Quantity of current can explain by quantity of water

That pass a pipe .

Current passes much to some actuator means that amount

Of electric power is strong .


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VoltageVoltage

Voltage symbol : E

Voltage unit : V

E = W (joule)/Q (coulombs) Volt

W : Electric powerQ : Electric charge amount

1 volt : 0.001

1 volt : 1,000:

1 : 1,000 v


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Potential and potential differencePotential and potential difference

11

Water level

difference

(Potential

difference)Water level12(Potential)

Water level 0

(Ground)

Water tank A(Positive terminal)

Water tank B(Negative terminal)

Water current

(Electrical current)

Electrical Potential

When there is electrical potential between A and b, current flowing .

- Water tank A (positive potential) : 12

- Water tank B (Negative potential) : 0


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Potential & potential difference 2Potential & potential difference 2+(Positive)

12 Volt

BATTERY

A

B

C D

E

F

-(Negative)

Switch

Lamp

Voltage measure position Switch ON condition (Lamp ON) Switch OFF condition (Lamp ON)

A ~ B

B ~ C

C ~ D

D ~ E

E ~ F

F ~ A

C ~ E

C ~ F

D ~ F


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Potential & potential difference 3Potential & potential difference 3

FUSE F8

5A

C224

BATTERY

COMPARTMENT

FUSE BOX

# 1

0.5R/L

0.5R/L

0.5R/L

0.5 B

ROOM

LAMP

SWITCH

C40-1

C40-2

CR02

R25

R26

ROOM LAMP

G09

12 Volt

Battery

Battery earth

Battery +Battery -

To measure each position for voltage


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ResistanceResistance

The electric resistance in a material is changed

According to the following variables:

- Kind of material- Sectional area of wire

- Length of wire

- Temperature


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ResistanceResistance

Resistance relation formula

R = L S

R : Resistance of material

: An invariable by kind of material ( m)

L : Length of wire (m)

S : Sectional area ()


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Current, Voltage, and ResistanceCurrent, Voltage, and Resistance

relationrelation

Current : A measure of the amount of electron flow .

Like a water pipe, the larger the pipe the greater the capacity to carry flow .Measured in "Amperes", or "Amps" (A) .

Voltage : A measure of the potential of a source to supply electromotive force (EMF), or

Electrical pressure .

Measured in Volts (V) .

Resistance : A measure of the opposition to current flow in a circuit .

Measured in Ohms ()

P

P1 P2 Pascal Pb

Pump

Actuator

Pactator


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Current, Voltage, and ResistanceCurrent, Voltage, and Resistance

SummarySummaryCurrent

Voltage

Resistance

VoltageCurrent

Resistance


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Series circuit in BatterySeries circuit in Battery

Total battery voltage

1.5 volt

4 batteries = 6 volt

Total battery voltage

12 volt 2 batteries = 24 volt

Battery series connect

- Voltage : Increase

- Current : Equality


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Series circuit in CircuitSeries circuit in Circuit

R1 R2

I1 I2I

E : 12 Volt

R1 R2

I1 I2I

E:12 Volt

Lamp1 Lamp2

Direct circuit of equivalence------------------------ Direct circuit of 2 lamps

Characteristic of series connection in circuit .

At series connection of resistance, total resistance increases connect resistance .

Total resistance increases, flowing current decreases in circuit .

Flowing current is always same in series circuit even if measure in any place .


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Load in directLoad in direct--current circuitcurrent circuitCircuit with load in direct-current circuit

V = (R1 R0) I

Rtotal = R1 R0

R1 : Load (Resistance)

R0 : Wire line resistance

I = V (R1 R0)R1 R0

I

V


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o ca cu a e o en vo age oo ca cu a e o en vo age o

resistanceresistance

12 Volt

R1=1; R2=2; R3=;

E1=? v E2=?v E3=?v

2A1=2V 2A2=4V 2A3=6V

To calculate both end voltage of resistance in D.C circuit

Total resistance R = 1 2 3 = 6 Ohm

Current I = 12Volts 6Ohms = 2 Amp.

1 ) E 1 = I R1

12V = 2A 1 = 2 volt

2 ) E 2 = I R112V = 2A 2 = 4 volt

3) E3 = I R3

12V = 2A 3 = 6 volt

E total = E1 E2 E3

= 2volt 4volt 6volt

= 12 Volt


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easuremen or curren aneasuremen or curren an

voltagevoltage

V

+

-

Volt meter

+

-

Ampere meter

A

Voltage measurement in direct current circuit . Parallel connected voltage meter .

Voltage measurement in direct current circuit . Parallel connected voltage meter .


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ParallelParallel circuit in Batterycircuit in BatteryCharacteristic

Parallel connection ofbatteries

Voltage : Constant

Capacity ofbattery : Increase


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ParallelParallel CircuitCircuitCharacteristic

Parallel connect in connection of circuit

- As much as connect resistance in parallel circuit, total resistance

decreases.

- As much as connect resistance in parallel circuit, total current

increase.

R2E R1 I 1E1I 2E2


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a cu a e es s ance n ara ea cu a e es s ance n ara e

circuit 1circuit 1To calculate easily total resistance

Rtotal = Multiplication of total resistance Sum of total resistance

Rtotal = (R1 R2) (R1 + R2)

R2E R1I 1

E1I 2E2


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Calculate Current in ParallelCalculate Current in Parallel

circu

it 2circu

it 2A point cu

rrent = (I 1+I 2+I3) = B point c

urrent

Point C, D, E current : Current that each lamp consumes

Parallel equivalence circuit 3 lamp's parallel circuits

I

I1 sw1

I2 sw2

I3 sw3

A B

C

D

E

IR2

R3

I1

I2

I3E

E

R1


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SeriesSeries -- Parallel CircuitParallel CircuitTo Calculate :

Resistance

Current

Voltage

EE1

E2

R1 R2

I1 I2

I

R3

a

b

c

I

E1

E2

E

a

b

c

Rt R1&R2=(R1R2) / R1+R2

R3

I3 I3


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OhmOhms Laws Law

Any operating electrical circu

its mu

st have three factors,voltage, current, and resistance.

Their relationship can be described by Ohms Law statement.

Voltage(V) Current(I) Resistance(R)

UP UP SAME

SAME UP DOWN

SAME DOWN UP


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Ohms law formulaOhms law formula

To understand Ohms law formula

E = I R

I = E R

R = E I

E : Voltage

I : Current

R : Resistance

E

I R

Voltage

Current Resistance


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Determining Current in OhmDetermining Current in Ohmss

Law

Law

E = 12 volt

I = ?

R = 6 ;+

_

I = E / R

I = 12 volt / 6 ohms

I = 2 Amperes

E = 12 volt

I = ?

R = 1 2 ;

+

_

I = E / R

I = 12 volts / 12 ohms

I = 1 Amperes

when the resistance is doubled, the current is reduced to half its former value

Determining Current


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Determining Voltage & Resistance inDetermining Voltage & Resistance in

OhmOhms Laws Law

E = 12 volt

I = 3A

R = ? ;+

_

Determining Resistance

E = 12 volt

I = 3 ampere

R = ?

To calculate, divide 3 into

12 and the answer is 4;.

Determining Voltage

E = I R

E = 4 3

E = 12 volts

E = ? volt

I = 3A

R = 4 ;+

_


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Voltage Drop 1Voltage Drop 1 The voltage removed from the circuit by the load.

Load : Lamp, Actuator, or Resistance

The total voltage lost must equal the voltage applied.

E = 12 volt+

_

Impressed voltage = Voltage drop from actuator

12 volt

Switch


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Voltage Drop in CircuitVoltage Drop in Circuit

V2

Voltage

When switch ON 12 Volt in normality.

If lower than 12Volt, the lamp does not worknormality because it means that resistance

exists somewhere.

12VOLT

BATT.

SWITCH LAMP

V1

Voltage

when SW Off

= 12Voltwhen SW ON

=0 Volt

V4

12 volt

12

VOLT

G11

V1

8volt

V2

4volt

R1 R2

V3

SW ON :

0volt

SW Off :

12 Volt

ISW

G2

+

To understand voltage drop in equivalent circuit

Voltage Drop in Circuit


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KirchoffKirchoffs Law 1s Law 1(Current Law)(Current Law)Kirchoffs current law (Kirchoffs first law)

In circuit inflow current's sum and outflow sum of done current same .

Inflow current outflow current = 0

In this current flow below formula is formed in below circuit.

Formula

I1+I4(INPUT CURRENT) = I2+I3+I5(OUTPUT CURRENT)

I 1 = IN

I 5 = OUTI 2 = OUT

I 3 = OUTI 4 = IN

rc orc o s aw curren n c rcus aw curren n c rcu


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rc orc o s aw curren n c rcu s aw curren n c rcu

diagram.diagram.

R1 R2

I1 I2

E

I

In series circuit

I = ?

I = ( ) current,I1 = ( ) of R1

I2 = ( ) of R2

I

I 1

I 2

I 3

I 4

In parallel circuit

I = ?

I,I4 = ( ) current in circuit

I1 = ( ) oflamp1

I2 = ( ) oflamp2

I3 = ( ) of lamp

Kirchoffs current law


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KirchoffKirchoffs Law 2s Law 2 (Voltage Law)(Voltage Law)Kirchoffs voltage law (Kirchoffs second law)

Input source voltage Sum of voltage drop = 0

I

R1 R2

I1 I2

E1 E2

E1 = ( ) VoltE2 = ( ) Volt

E = ( ) Kirchoffs voltage law

E = ( )

= (R1I) + (R2 I)= (R1 + R2) I


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Electric power and WattElectric power and Watt

Amount of work that electricity during 1 second.

Amount ofelectrical energy, that consume during per time.

Expression of electric power : P

Unit of electric power : w(watt)

The formula for electric power is :

P(watt) = E(volt)

I(current) = E

E/R = E2

/R = E

E = P/I

I = P/E


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Summary for basicElectrical 1Summary for basicElectrical 1Troubleshooting method in circuit

M

A

B C

D

E

E

When switch on motor's operation is not smooth in below circuit,it explains checking method and inspection order.

Check procedure

1st. Measure the voltage of battery.

2nd, 1st. Measure the voltage of between B and C.

At this time, voltage must be 12 volts, and inspect following below order if is low than applied voltage.

And, if voltage are 12 volts, it is motor itself defect.

3rd, Measure the voltage between A and B

At this time, voltage bust be 0 volt, if higher than 0 volt, there is resistance between A and B.

4th, Measure the voltage between C and E

At this time, voltage bust be 0 volt, if higher than 0 volt, there is resistance between C and E.


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Summary for basicElectrical 2Summary for basicElectrical 2C

heck for grou

nd condition in Parallel circu

it

I

I1

I2

I3I 4

Switch1

Switch2

Switch3

VOLT

- Current I4 is different according to switch ON in above circuit diagram.

- And voltage V is different according to ground connection condition.

If it is normally, voltage V become 0volt


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Summary for basicElectrical 3Summary for basicElectrical 3Troubleshooting a series circuit

The voltmeter will now

read the amount ofvoltage drop across R1.

When the switch is closed,

the voltmeter will indicatezero volts across the switch.

12

VOLT

R2 SW

G11

I

G2

+

R1

12

VOLT

G11

R2I

G2

+

SWR1

With the switch open,

The voltmeter will read a full12-volt, the same as the source.

There is nothing volt

when the switch opened

V1V2

1. Measure voltage

2. Measure voltage


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Summary for basicElectrical 4Summary for basicElectrical 4Troubleshooting a parallel

Caution

The switch must be open or the power source disconnected when measuring

resistance using by ohmmeter.

Measure resistance 10;

Calculated resistance 5;

An ohmmeter can provide a quick idea about

the condition of the circuit.

An infinity reading would indicated an open, and

a zero resistance reading would indicate a short circuit.

12

VOLTR2=10;

I

Open

+

R1=10;

Switchopen

1. Measure resistance


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Summary for basicElectrical 5Summary for basicElectrical 5Troubleshooting a parallel

2. Measure current

An ammeter can be connected across the open switch,

It can measure the full load current of the circuit

The switch location of a circuit is an ideal location to connect an ammeter to the circuit.

R2

I

+

R1

Switch


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Summary for basicElectrical 6Summary for basicElectrical 6Troubleshooting series-parallel circuit

1. Measure voltage in series-parallel circuit

Measure voltage : 12 volt

12

VOLTR3G11

I

Open+

R2

Switch

R1


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Summary for basicElectrical 7Summary for basicElectrical 7Troubleshooting series-parallel circuit2. Measure current in series-parallel circuit

12

VOLTR3

G11

I

Open+

R2

Switch

R1

12

VOLT R3G11

I

Open

+

R2

SwitchR1

3. Measure resistance in series-parallel circuit


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Analog Multi meterAnalog Multi meter

N S

Very thin wire

Would on

Meter

Negative lead wirePositive lead wire

Indicate needle Spring

Scale

South field poleNorth field pole

Analog Multi Meter's operation principle


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Analog Current meterAnalog Current meterAn ammeter measures electrical current in a circuit.

M

R=100

R=11.1

0~1

0~10

0~50

0~100 R=1.04

R=1.01

Range Switch


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Analog Volt meterAnalog Volt meter

Analog voltmeter circuit

M

R=100

R=9.9 k

0~1

0~10

0~50

0~100R=99.9 k

R=499.9 k

0~500

R=900

Voltmeters are always connected in parallel with the device being measured


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Analog OhmmeterAnalog Ohmmeter

0

48

12

3 volt Battery

Black lead wireRed lead wire Resistor

Resistance scale

Zero AdjusterElectric

Magnetic

For Measure

Data indicate.

Ohmmeter circuit in case


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Characteristics ofAnalogCharacteristics ofAnalog

OhmmeterOhmmeterVoltage that important thing is measuring in resistance mode voltageoutput through lead wire are 3volt and 12volt according to ohm modeswitch position.

Range 1, 10, 1k : 3-volt output

Range10k : 12 volt(3volt+9volt) output

025

Polarity:+ Polarity:- Polarity:+Polarity:-


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DigitalmultiDigitalmulti--metersmeters


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Digital multiDigital multi--metersmeters SummarySummary

Summary for Analog multi meter When measure voltage, connect by parallel.

When measure current, connect by series connection.

Even if do not know measurement value, range establishment is

no necessity.

When there is selective switch to resistance mode, voltage is

output through probe.

- Ou

tpu

t voltage : 0.25 volt At this time, voltage output from read lead wire , and from

black lead wire - volt.


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Magnet and Magnetic ForceMagnet and Magnetic ForceCharacteristic of magnetic substance andM

agnetic line of force Magnetic line of force comes out from N pole and enter into S pole. Direction of magnetic line of force indicates the direction of the

magnetic field.

Density of magnetic line of force(Density of magnetic flux)indicates strength of magnetic field

Magnetic lines of force does not cross each other. If the direction of magnetic lines of force is same, those magnetic

lines repel each other.

Magnetic line of force and Magnetic field.

Magnetic line of force : Imagined line which stands for electricforce have the characteristic pass the non-magnetic substance.

Magnetic field : Modification of space so that force appear onmagnetic poles or magnets


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Magnet and Magnetic ForceMagnet and Magnetic Force

These figure show the magnetic fieldof attracting and repelling magnets.

The earth is a large magnetic,surrounded by a magnetic field.

d id i


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NN SS NN SS

Magnet and Magnetic ForceMagnet and Magnetic Force If the magnetic substance ( Iron, Nickel, Tungsten ),If the magnetic substance ( Iron, Nickel, Tungsten ),

which is not magnet, is close to magnet, the magneticwhich is not magnet, is close to magnet, the magneticsubstances become a magnet .substances become a magnet .

Phenomenon that material get magnetic force withinPhenomenon that material get magnetic force within

magnetic field.magnetic field.

Magnet Magnetic

Substance

NN SS NN SS

Magnetic

Substance

Magnetic

Substance

l i d il i d i


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Magnetic field by electricchargeMagnetic field by electricchargeCurrent

Iron pieces

wire

Battery

Electro Magnetic InductionElectro Magnetic Induction

El M i I d iEl M i I d i


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Electro Magnetic InductionElectro Magnetic InductionMagnetic field around coil

M i Fl (LM i Fl (L L )L )


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Magnetic Flux (LenzMagnetic Flux (Lenzs Law)s Law)

LenzLenzs law states when a change in thes law states when a change in the

magnetic fluxmagnetic flux

occurs, then there are induced currents thatoccurs, then there are induced currents that

opposeoppose

the change in flux.the change in flux.

S l idS l id


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SolenoidSolenoid

When a current carrying conductor is wouldWhen a current carrying conductor is would

into a coil, orinto a coil, orsolenoidsolenoid, the magnetic fields, the magnetic fields

circling conductors seem to merge or joincircling conductors seem to merge or join

together.together.

A solenoid will appear as a magnetic fieldA solenoid will appear as a magnetic field

with a North Pole at one end, and s South Polewith a North Pole at one end, and s South Pole

at the opposite end.at the opposite end.

Current in

Current out

S

N

R lR l


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RelayRelay TheThe relayrelay isis aa devicedevice usedused toto controlcontrol aa largelarge flowflow ofof

currentcurrent byby meansmeans ofofaa lowlow voltage,voltage, lowlow currentcurrent circuitcircuit..

AA relayrelay isis aa magneticmagnetic switchswitch..

WhenWhen aa relayrelayss coilcoil isis magnetized,magnetized, itsits attractiveattractive forceforce

pullspulls thethe leverlever arm,arm, calledcalled armature,armature, towardtoward thethe coilcoil.. TheThe

contactcontact pointspoints onon thethe armaturearmature willwill openopen or or closeclosedependingdepending onon theirtheir normallynormally atat restrest positionposition..

T fT f


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TransformerTransformer AAtransformertransformer is a device used to transfer energy fromis a device used to transfer energy from

one circuit to another using electromagnetic induction. Aone circuit to another using electromagnetic induction. A

transformer consists of two or more coils ofwire woundtransformer consists of two or more coils ofwire wound

around a common laminated iron core.around a common laminated iron core.

Thefirst winding, which is the input winding, is calledThe

first winding, which is the input winding, is calledthe primary. This winding receives the energy from thethe primary. This winding receives the energy from the

source. The second winding, which is output winding, issource. The second winding, which is output winding, is

called the secondary. The output load is attached to thecalled the secondary. The output load is attached to the

secondary.secondary.

Primary Secondary

T fT f


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TransformerTransformer InductionInduction

CoilCoil AA producesproduces aa risingrising andand collapsingcollapsing magneticmagneticfield

fieldthatthat cutscuts acrossacross thethe conductorsconductors inin coilcoil BB.. CoilCoil BB hashas aa

voltagevoltage inducedinduced byby thethe electricalelectrical actionaction ofof coilcoil AA.. thisthis isis

thethe principleprinciple behindbehind allall transformers,transformers, thisthis principleprinciple isis

calledcalledmutualmutual inductioninduction..

IfIf thethe acac voltagevoltage sourcesource frequencyfrequency isis equalequal toto 6060 Hz,Hz, thenthen

thethe magneticmagnetic fieldfield risesrises andand collapsescollapses 120120 timestimes aa secondsecond..

Primary

Coil ASecondaryCoil B

T fT f


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Turns Ratio PrincipleTurns Ratio Principle

TheThe ratioratio betweenbetween thethe numbernumber ofof turnsturns inin thethe primaryprimary andand

secondarysecondary isis calledcalled thethe turnturnss ratioratio.. TheThe turnturnss ratioratio isis

simplysimply thethe numbernumber ofof turnsturns inin thethe primaryprimary divideddivided byby thethe

numbernumber ofof turnsturns inin thethe secondarysecondary.. WrittenWritten asas aa formulaformula::

TurnsTurns ratioratio == NpNp // Ns=Ns=1010//11 oror 1010 toto 11

TransformerTransformer

Voltage is step down.

1,000 turns 100 turns

120 V 12 V

10 to 1 ratio

12 V


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TransformerTransformer TheThe voltagevoltage ratioratio isis thethe ratioratio betweenbetween thethe voltagesvoltages ofof thethe

primaryprimary andand secondarysecondary.. ItIt isis inin thethe samesame proportionproportion asas thetheturnturnss ratioratio::

VoltageVoltage ratioratio == EpEp // EsEs == NpNp // NsNs

TheThe currentcurrent ratioratio isis thethe ratioratio betweenbetween thethe currentscurrents inin thetheprimaryprimary andand secondarysecondary.. ItIt isis inin inverseinverse proportionproportion toto thethe

turnturnss ratioratio::

CurrentCurrent ratioratio == IsIs // IpIp == NpNp // NsNs

CombiningCombining thethe threethree ratiosratios::

EpEp // EsEs == NpNp // NsNs == IsIs // IpIp


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TransformerTransformer TransformersTransformers thatthat areare usedused toto raiseraise oror lowerlower aa voltagevoltage areare

knownknown asas stepstep upup transformerstransformers andand stepstep downdowntransformerstransformers..

StepStep upup transformerstransformers havehave moremore turnsturns inin thethe secondarysecondary

thanthan thethe primaryprimary.. TheThe voltagevoltage isis increased,increased, itit stepssteps upup..

StepStep downdown transformerstransformers havehave fewerfewer turnsturns inin thethesecondarysecondary thanthan thethe primaryprimary.. TheThe voltagevoltage isis decreased,decreased, itit

stepssteps downdown..


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Automobile Ignition CoilAutomobile Ignition Coil The ignition coil produces the high voltageThe ignition coil produces the high voltage

spark in an automobile electrical system. Itspark in an automobile electrical system. It

uses a high turns ratio to develop 30,000 voltsuses a high turns ratio to develop 30,000 volts

or more across the spark plug gap.or more across the spark plug gap.

Ignition switch

Battery 12V

Ignition coil

Distributor

Spark plug

ECM

LL LL


70/108

Surge voltage by selfSurge voltage by self--induction actioninduction action

Practice 1)Practice 1)

EvaluationEvaluation

T

V

12V BATT

+-

LenzLenzs Laws Law

LL LL


71/108

Practice 2)Practice 2)

EvaluationEvaluation V

T

12V BATT

+-

LenzLenzs Laws Law

LL LL


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EvaluationEvaluation

N S Conductor

LenzLenzs Laws Law

V

T


73/108

CAPACITORCAPACITOR A capacitor is a device that temporarily stores anA capacitor is a device that temporarily stores an

electric charge. A capacitor accepts or returns thiselectric charge. A capacitor accepts or returns this

charge in order to maintain a constant voltage.charge in order to maintain a constant voltage.

As the switch is closed, electrons from theAs the switch is closed, electrons from the

negative terminal of the source flow to one platenegative terminal of the source flow to one plateof the capacitor.of the capacitor.

These electrons repel electrons from the secondThese electrons repel electrons from the second

plate, which are then drawn to the positiveplate, which are then drawn to the positive

terminal of the source.terminal of the source.

The capacitor is now charged and is opposing theThe capacitor is now charged and is opposing the

source voltage.source voltage.Schematic symbols Basic Schematic diagram for capacitor.


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Conducti

l t s

i l ctric

Conducti

l t s

i l ctric

+-

+-

+-

+-


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Calculating CapacitanceCalculating Capacitance CapacitanceCapacitance isis determineddetermined byby thethe numbernumber ofofelectronselectrons thatthat

cancan bebe storedstored inin thethe capacitorcapacitor forfor eacheach voltvolt ofof appliedappliedvoltagevoltage..

CapacitanceCapacitance isis measuredmeasured inin faradsfarads (F)(F).. AA faradfarad representsrepresents

aa chargecharge ofof oneone coulombcoulomb thatthat raisesraises thethe potentialpotential 11--voltvolt..

ThisThis equationequation isis writtenwritten.. CC == QQ // EE

WhereWhere CC isis thethe capacitancecapacitance inin farads,farads, QQ isis thethe chargecharge inin

coulombs,coulombs, areare EE isis thethe voltagevoltage inin voltsvolts..

Capacitors used in electronic work have capacitiesCapacitors used in electronic work have capacities

measured in microfarads (1/1,000,000F) and Pico faradsmeasured in microfarads (1/1,000,000F) and Pico farads

(1/1,000,000 F).(1/1,000,000 F).

Microfarad is commonly written asMicrofarad is commonly written as. Pico farad is. Pico farad is

written aswritten as . Nan farad is not a common measurement of. Nan farad is not a common measurement of


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Types ofCapacitorsTypes ofCapacitors CapacitorsCapacitors areare mademade inin hundredshundreds ofofsizessizes andand typestypes..

Can type electrolyticcapacitorsCan type electrolyticcapacitors use differentuse different

methods ofplate construction.methods ofplate construction.

TheThe ceramiccapacitorceramiccapacitor is made ofa special ceramicis made ofa special ceramic

dielectric.dielectric. Mica capacitorsMica capacitors are small capacitors. They are madeare small capacitors. They are made

by stacking tinfoil plates together with thin sheets ofby stacking tinfoil plates together with thin sheets of

mica as the dielectric.mica as the dielectric.

Fixed paper capacitors , Rectangular oil filledFixed paper capacitors , Rectangular oil filledcapacitors, Tubular electrolytic capacitors, etc.capacitors, Tubular electrolytic capacitors, etc.


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Can type capacitors

Ceramic capacitor

Mica capacitor

T i t R f thT i t R f th


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Transient Response of theTransient Response of theCapacitorCapacitor

A capacitor and a resistor are connected inA capacitor and a resistor are connected in

series across a voltage source. A circuit thatseries across a voltage source. A circuit that

contains resistance and capacitance is calledcontains resistance and capacitance is called

an RC circuit.an RC circuit.

When the switch is closed in this RC circuit,When the switch is closed in this RC circuit,

the maximum current will flow. The currentthe maximum current will flow. The current

gradually decreases until the capacitor hasgradually decreases until the capacitor hasreached its full charge. The capacitor willreached its full charge. The capacitor will

charge to the level of the applied voltage.charge to the level of the applied voltage.


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Switc C

Batt r

Switc C

Batt r

E

I


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RC Time ConstantRC Time Constant

During the charge and discharge of the seriesDuring the charge and discharge of the seriesofnetwork outlined above, a period of timeofnetwork outlined above, a period of timeelapsed. This time is indicated along the base,elapsed. This time is indicated along the base,or xor x--axis, of the graphs.axis, of the graphs.

TheThe formulaformula toto determinedetermine thethe timetime constantconstant ininRCRC circuitcircuit isis:: == RR CC

Time

ER

Cha rge S te ady

stateDischarge

ER = IR

ER


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GENERATORSGENERATORS


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MagneticInductionMagneticInduction

When conductor acrossWhen conductor across the magnetic force line,the magnetic force line,

electromotive force iselectromotive force is

occurred in conductoroccurred in conductor

When conductorWhen conductor

moves inducedmoves induced voltage is generatedvoltage is generated

in the coil by inducedin the coil by induced

electromotive force.electromotive force.


VIron

T

S N

VIron

T

S N


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The action ofa coil turning in a magnetic field.The action ofa coil turning in a magnetic field. In position A, the coil top moves parallel to field ofIn position A, the coil top moves parallel to field of

magnetism. No voltage is produced.magnetism. No voltage is produced. I

n position B, both sides of

the coil are cutting thefield at

In position B, both sides o

fthe coil are cutting the

field atright angles. The highest voltage is produced at this rightright angles. The highest voltage is produced at this right

angle.angle. Position C is like position A, the voltage drops to zero.Position C is like position A, the voltage drops to zero. In position D, the coil is again cutting the field at rightIn position D, the coil is again cutting the field at right

angles, where the highest voltage is induced. However, inangles, where the highest voltage is induced. However, in

position D the voltage is in the opposite direction of thatposition D the voltage is in the opposite direction of that


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Construction ofa GeneratorConstruction ofa Generator When dc is desired in theWhen dc is desired in the

outside circuit, a set ofoutside circuit, a set of

commutator segments and acommutator segments and a

set ofbrushes are used.set ofbrushes are used.

The mechanical connectionThe mechanical connection

between the outside circuitbetween the outside circuitand the armature constantlyand the armature constantly

changes because of the brushchanges because of the brush

and commutator connections.and commutator connections.

The action of the commutatorThe action of the commutatorand brushes maintains aand brushes maintains a

constant flow in one directionconstant flow in one direction

toward the outside circuit.toward the outside circuit.


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Construction ofa GeneratorConstruction ofa Generator TheThe currentcurrent inin thethe outsideoutside circuitcircuit ofof thethe dcdc

generatorgenerator alwaysalways flowsflows inin oneone directiondirection.. TheTheoutputoutput voltagevoltage ofof thethe generatorgenerator risesrises andand fallsfalls

fromfrom zerozero toto aa maximummaximum toto zero,zero, butbut alwaysalways inin

thethe samesame directiondirection.. The output is not a smooth direct current. The

weakness of pulsating dc can be improved two ways.The number of rotating coils on the armature can beincreased and commutator sections can be supplied

for each set of coils.


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Types ofGenerationsTypes ofGenerations

Generator output is determined by the strength ofGenerator output is determined by the strength o

fthe magnetic field and the speed of rotation. Fieldthe magnetic field and the speed of rotation. Field

strength is measured in amperestrength is measured in ampere--turns. So, anturns. So, an

increase in current in the field windings willincrease in current in the field windings will

increase the times the speed of rotation.increase the times the speed of rotation. Separately Excited Field GeneratorSeparately Excited Field Generator

ThisThis isis thethe separatelyseparately excitedexcited fieldfield generatorgenerator..

WithWith thethe speedspeed constant,constant, thethe outputoutput maymay bebe variedvariedbyby controllingcontrolling thethe excitingexciting voltagevoltage ofof thethe dcdc

sourcesource.. ThisThis isis donedone byby insertinginserting resistanceresistance inin

seriesseries withwith thethe sourcesource andand fieldfield windingswindings..


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Types ofGenerationsTypes ofGenerations SelfExcited GeneratorSelfExcited Generator

A selfA self--exited generator uses no separate sourceexited generator uses no separate source

ofvoltage to excite the generatorfield winding.ofvoltage to excite the generatorfield winding.

The selfThe self--excited generator produces a smallexcited generator produces a small

voltage when the armature windings cut acrossvoltage when the armature windings cut acrossa weak magnetic field.a weak magnetic field.

Shunt generatorShunt generator

The shunt generator derives its name fromThe shunt generator derives its name fromthe way the field pole coils are connected inthe way the field pole coils are connected in

parallel to the armatureparallel to the armature..


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Types ofGenerationsTypes ofGenerations Series generatorSeries generator

The series generator is so named because itsThe series generator is so named because itsfield windings are wired in series with thefield windings are wired in series with the

armature and the load.armature and the load.

Because of the wide difference in outputBecause of the wide difference in outputvoltage, it is not a very practical generator tovoltage, it is not a very practical generator to

use if the load varies.use if the load varies. Compound generator

The compound generator uses both series and shuntwindings in the field. The series windings are often a fewturns of large wire. The wire size of the series windings isusually the same size as the armature conductors.


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Alternating CurrentAlternating Current Alternating current changes its direction ofAlternating current changes its direction of

flow at times in the circuit. In dc, the sourceflow at times in the circuit. In dc, the source

voltage does not change its polarity. In ac, thevoltage does not change its polarity. In ac, the

source voltage changes its polarity betweensource voltage changes its polarity between

positive and negative.positive and negative. A cycle is a sequence or chain ofeventsA cycle is a sequence or chain ofevents

occurring in a period of time. An ac cycle canoccurring in a period of time. An ac cycle can

be described as a complete set of

positive andbe described as a complete set of

positive andnegative values for ac.negative values for ac.

Frequency, measured in cycles per second orFrequency, measured in cycles per second or

hertz (Hz), is the number ofcomplete cycleshertz (Hz), is the number ofcomplete cycles


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AlternatorAlternator The alternator is used in the charging systemThe alternator is used in the charging system

ofall vehicles.ofall vehicles.

The output is rectified from alternating currentThe output is rectified from alternating current

to direct current for charging the battery andto direct current for charging the battery and

other electrical devices in the vehicle. Theother electrical devices in the vehicle. The

alternator has some advantages over the dcalternator has some advantages over the dc

generator. These advantages include highergenerator. These advantages include higher

output at lower speeds.output at lower speeds.


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AlternatorAlternator The alternator is a brush type in which a current flows fromThe alternator is a brush type in which a current flows from

the brushes through the slip ring to the field coil in the rotor.the brushes through the slip ring to the field coil in the rotor. Major componentsMajor components

Rotor (field coil): generatesmagnetic fieldRotor (field coil): generatesmagnetic field

WhenWhen thethe rotorrotor isis drivendriven byby thethe pulleypulley rotation,rotation, aa currentcurrent

flowsflows fromfrom thethe bushes,bushes, throughthrough thethe slipslip ring,ring, toto thethe fieldfield coilcoil..TheThe rotorrotor corecore tabstabs thenthen becomebecome magneticmagnetic polepole..


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i i i li i i l


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Motor Operation PrinciplesMotor Operation Principles

A Magnetic field exists between the

poles of a permanent magnet. The

arrows indicate the direction of the field.

A current carrying conductor has a

magnetic field; its direction depends

on the direction of the current.

TheThe electricmotorelectricmotor converts electrical power into rotatingconverts electrical power into rotating

mechanical power.mechanical power.

RotationalRotational forceforce comescomes fromfrom thethe interactioninteraction betweenbetween thethemagneticmagnetic fieldfield foundfound aroundaround aa currentcurrent carryingcarrying conductorconductorandand aa fixedfixed magneticmagnetic fieldfield..

AA conductorconductor carryingcarrying aa currentcurrent hashas aa magneticmagnetic fieldfieldaroundaround itit.. TheThe directiondirection ofof thethe fieldfield dependsdepends onon thethedirectiondirection ofof thethe currentcurrent..

O i i i lO i i i l


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Motor Operation PrinciplesMotor Operation Principles

The field around the conductor flows with

the permanent field above the conductor

but opposes the permanent field below

the conductor. The conductor will movetoward the weakened field.

The current has been reversed in the

conductor, causing the conductor field to

reverse. Now the field is reinforced

below the conductor and weakenedabove the conductor. The conductor will

move up.

The single conductor is replaced by a coil of

conductors wound in the slots of an armature

core. Notice how the interaction of the two fields

will produce rotation. Coil A moves up and coil B

moves down. The rotation is clockwise.

C El i FC El i F


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CounterElectromotive ForceCounterElectromotive Force AA conductorconductor cutscuts throughthrough aa magneticmagnetic field,field, voltagevoltage isis

inducedinduced inin thethe movingmoving conductorconductor.. WhenWhen thethe armaturearmature beginsbegins toto rotate,rotate, thethe motormotor alsoalso

becomesbecomes aa generatorgenerator..

The generated electrical force that opposes the appliedThe generated electrical force that opposes the applied

emf is called counter electromotive force.emf is called counter electromotive force.

Take note of the polarity of the generator output with a clockwise rotation.

The motor requires the opposite polarity for aclockwise rotation

DC MDC M


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DC MotorsDC Motors The different types ofdc motors share theThe different types ofdc motors share the

common names ofdc generators such as shunt,common names ofdc generators such as shunt,series, and compound.series, and compound.

The construction of the motors is similar to theThe construction of the motors is similar to the

generator counter parts.generator counter parts.

shunt motor series motor Compound

motor

S MS M


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Starter MotorStarter Motor The starter is a reductionThe starter is a reduction

starter with astarter with a

builtbuilt--in reduction gear. Itsin reduction gear. Its

motor hasmotor has

been downsized with evenbeen downsized with evenhigherhigher

speed capability.speed capability.


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St t M t O tiSt t M t O ti


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Starter Motor OperationStarter Motor Operation When the starter switch is ON.When the starter switch is ON.

1. Current from the battery flows from the terminal1. Current from the battery flows from the terminal SS ofofthe magnetic switch to the pullthe magnetic switch to the pull--in coilin coil PP and holdingand holdingcoilcoil HH..

2. The plunger, attracted by the magnetic flux of the pull2. The plunger, attracted by the magnetic flux of the pull--

in coil and holding coil pushes out the pinion.in coil and holding coil pushes out the pinion.

3. When the pinion engages with the ring gear, the3. When the pinion engages with the ring gear, thecontactcontact P2P2 closes.closes.

4. The large current directly flows from battery to the4. The large current directly flows from battery to the

motor.motor. 5. Turn the pinion.5. Turn the pinion.

6. No current flows to the pull6. No current flows to the pull--in coil.in coil.

St t M t O tiSt t M t O ti


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Starter Motor OperationStarter Motor Operation

Basic Electrik

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