Applied basic electricity workshop

Applied Basic Electricity

www.spacetec.org

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Never touch a

downed wire

Don’t bring

appliances

near water

Stay clear

of power

lines

NO power

tools on

wet grass

or wet surfaces

Ground Fault Circuit

Interruptors on ALL outdoor

electrical outlets

(GFCI)

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Pull the plug

not the cord

Keep cords

away from

heat and

water

Never run

under

carpets

Electricity and

water don’t mix

Never remove

the ground

prong

Eliminate octopus

connections

Check cords

and plugs for

wear

Don’t use

cords as

permanent

wiring

Don’t pry

toast from a

plugged-in

toaster

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Wear appropriate attire

Hard hat

Goggles

Tight clothing

No rings

Or metal jewelry

Safety shoes

Lockout

TagoutWear earmuffs

in noisy areas

Confine long hair or keep

It trimmed when working

Around machinery

Breathing

Protection

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Less than 1 ampere

can cause death

SEVERE SHOCK

MILD SHOCK

SEVERVE BURNS-

BREATHING STOPS

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Body Resistance and Shock

• Electrical resistance is defined as the opposition to flow of current in a circuit

• Resistance is measured in OHMS

• The lower the body resistance, the greater the potential shock hazard

• Body resistance can be measured with an ohm meter

• Any current flow above 5 milli-amperes is considered dangerous

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Skin Conditions and Resistance

• Dry skin resistance: 100,000 to 600,000 Ohms

• Wet skin resistance: 1,000 Ohms

• Internal body….hand to foot: 400 to 600 Ohms

• Ear to ear: about 100 Ohms

• Burns and neurological damage are the most common injuries caused by electrical shock

THE DANGER OF HARMFUL SHOCK INCREASES

AS THE VOLTAGE INCREASE

VOLTAGES AS LOW AS 30V Can Be Dangerous !!

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First Aid For Electrical Shock

• Turn power OFF & remove victim from electric contact.

• Do Not touch victim until power is removed.

• Apply artificial respiration if not breathing. Keep victim warm.

• Keep victim head low so blood can flow to brain. Avoid placing victim where breathing obstruction may occur.

• Cold water or ice pack for first degree and minor second degree.

• Don’t break blisters ! For open blisters…no water or cold packs…use thick clean bandages to avoid infection.

• Do not remove charred clothing ..let a medical pro do it..

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Know where the fire extinguisher is and how to use it

CLASS

A

CLASS

B

CLASS

C

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HAZARDOUS PROPERTIES

Corrosive Ignitable Toxic Reactive

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GFCI Block Diagram

Circuit

BreakerGFCI Wall Plug

Trip Requirements:

• 10 millisecond response time

• 5 milliamp difference in outgoing and returning current

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AFCI Circuit Example

Reference: www.iaei.org

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Arc Fault Circuit Interrupter (AFCI)

• AFCI is expected to provide enhanced

protection from arcing and sparking

• AFCIs are intended to address fire hazards;

GFCIs address shock hazards

• NEC 2002 will require AFCIs for bedroom

circuits in new residential construction,

effective January 2002

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Static Electricity

STATIC:

• Having no motion; at rest

STATIC ELECTRICITY:

• Electrical charge at rest.

FYI

• Electrical charges are caused by an

imbalance of electrons on the surface

atoms of materials.

• Primarily due to triboelectric charging

between materials where electrons from

surface atoms are transferred between

materials creating an electrostatic

potential.

• Electrostatic field surrounds

electrostatically charged objects. ESD: A hare raising experience

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Producing Static Electricity by Friction

Fur and rubber

rod rubbed togetherCharge accumulates

at end of rod only

Electrons move from

the fur to the rod

Negative charge

produced on the rod

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Law of Electric Charges

(Law of Electrostatics)

Like charges repel

Unlike charges attract

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Electrostatic Discharge

(ESD)

DEFINITION:

A transfer of

electrostatic charge

between bodies at

different electrostatic

potentials caused by

direct contact or

induced by an

electrostatic field.

Lightning: a mega ESD event

Lightning strikes somewhere on Earth about 100 times each second!

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ESD Damage

• Can damage electronic components at any time

– During shipping, should use special bags (pink)

– During component installation

– During board installation

– During handling (ex. Storage area to workbench)

– During storage

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Wrist Straps

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Electrostatic Protection

• Electronic parts can be easily destroyed by electrostatic discharge

• Wearing a wrist strap tied to the local ground is the most important thing you can do to control electrostatic discharge (ESD)

• Wrist straps need to be checked once a week

• A static meter can be used to detect and measure electrostatic charge

• Follow the ESD procedures used by your employer

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Basic Electrical Formulas

&

Calculations

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The Powers of Ten and Scientific Notation. It is often used in electronics to

express very large numbers and very small numbers. Very small numbers are

expressed by using negative powers of ten. For example, 3.2 x 10-8 is a

scientific notation for the number 0.000000032. Here, “ten to the minus

eight power” means “move the decimal place in 3.2 eight places to the left.”

Metric and Prefix Notations

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Number Prefix Symbol

10 1 deka- da

10 2 hecto- h

10 3 kilo- k

10 6 mega- M

10 9 giga- G

10 12 tera- T

10 15 peta- P

10 18 exa- E

10 21 zeta- Z

10 24 yotta- Y

Number Prefix Symbol

10 -1 deci- d

10 -2 centi- c

10 -3 milli- m

10 -6 micro- µ(greek mu)

10 -9 nano- n

10 -12 pico- p

10 -15 femto- f

10 -18 atto- a

10 -21 zepto- z

10 -24 yocto- y

Note: Symbols in red are most used……know them

Metric and Prefix Notations

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Prefix Examples

0.002A = 2 X 10-3A = 2mA

100kV = 100 X 10+3V = 1 x 10+5V= 100,000V

100µs = 100 x 10-6s = 1 x 10-4s = 0.0001s

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Structure of an atom

Neutron (No Charge)

Proton

(Positive Charge)

Electron

(Negative Charge)

Shell or

energy level

Most of the mass of an atom is located in its nucleus

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Electron Configuration

• The Electron Configuration is the orbital description of the locations of the electrons in an unexcited atom

• Electrons orbit in “SHELLS” or “Energy Levels”

• The higher the orbit, the higher the “Energy Level”

• Atoms react based on the Electron Configuration

• The outermost electron shell is the most important as far as conductivity properties are concerned

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13 P

14 N

Bohr model of the aluminum atom

13=13

Protons = Electrons

Net charge is neutral or zero

Electrically Neutral

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Placement of electrons in a copper atom

+29

Complete with 2

Complete with 8

Complete with 18

Incomplete with 1

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Electricity-the flow of free electrons

Bound electron Free electron

Valance electron

Negative source

Positive source

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Atomic structure of conductors,

insulators, and semiconductors

Insulator - full

valence shell

Conductor - 1 to 3

valence electrons

Semiconductor - 4

valence electrons

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Multimeter

•voltage

•current

•resistance

Voltage tester

•voltage level

•rugged construction

Clip-on ammeter

measures current

without direct

connection

Digital circuit probe

measures digital

logic levels

Oscilloscope

used to measure

and examine

voltage waveforms

Instruments

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Meter Safety

• Never use an ohmmeter on a live circuit

• Never connect an ammeter in parallel with a voltage source

• Use proper range settings: Do NOT overload a meter

• Do not short terminals using meter probes

• Never measure unknown high voltages: find out the range before attaching a meter

• Check for frayed or broken meter leads

• Avoid touching exposed meter probes

• If possible, connect meter before applying power to circuit

• When connecting a meter to a live circuit work with one hand at your side to lessen the danger of shock

• To reduce the danger of accidental shock, disconnect meter test leads immediately after completing a measurement

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Megger Safety Precautions

Megger Safety Precautions

• When you use a megger, you could be injured or damage equipment you are working on if the following MINIMUMsafety precautions are not observed.

– Use meggers on high-resistance measurements only (such as insulation measurements or to check two separate conductors on a cable).

– Never touch the test leads while the handle is being cranked. ·

– Deenergize and discharge the circuit completely before connecting a megger.

– Disconnect the item being checked from other circuitry, if possible, before using a megger.

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Megger’s• For maximum safety, most meggers are

equipped with hand-crank generators for producing the high DC voltage (up to 1000 volts). If the operator of the meter receives a shock from the high voltage, the condition will be self-correcting, as he or she will naturally stop cranking the generator! A simple hand-crank megger is shown in this photograph:

• Some meggers are battery-powered to provide greater precision in output voltage. For safety reasons these meggers are activated by a momentary-contact pushbutton switch, so the switch cannot be left in the "on" position and pose a significant shock hazard to the meter operator.

• Real meggers are equipped with three connection terminals, labeled Line, Earth, and Guard.

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Megger Use

• Meggers are field instruments: that is, they are designed to be portable and operated by a technician on the job site with as much ease as a regular ohmmeter. They are very useful for checking high-resistance "short" failures between wires caused by wet or degraded insulation. Because they utilize such high voltages, they are not as affected by stray voltages (voltages less than 1 volt produced by electrochemical reactions between conductors, or "induced" by neighboring magnetic fields) as ordinary ohmmeters.

• For a more thorough test of wire insulation, another high-voltage ohmmeter commonly called a hi-pot tester is used. These specialized instruments produce voltages in excess of 1 kV, and may be used for testing the insulating effectiveness of oil, ceramic insulators, and even the integrity of other high-voltage instruments. Because they are capable of producing such high voltages, they must be operated with the utmost care, and only by trained personnel.

• It should be noted that hi-pot testers and even meggers (in certain conditions) are capable of damaging wire insulation if incorrectly used. Once an insulating material has been subjected to breakdown by the application of an excessive voltage, its ability to electrically insulate will be compromised. Again, these instruments are to be used only by trained personnel.

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GENERIC CIRCUIT

Electron

current

flow

Control

Device

Power

Source

Load

Device

Conductor

Protective

Device

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VOLTAGE- The difference in electric

charge between two points.

1 Volt

- Difference in

Electric Charge

1 Ohm

of Resistance

Produces 1 Ampere

of Current Flow.

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VOLTAGE = Electromotive Force

• Voltage, also called electromotive force, is a

quantitative expression of the potential

difference in charge between two points in an

electrical field.

• For electrons to flow, there must be a source of

electromotive force (emf), or voltage

• Electromotive force can be produced by a variety

of different primary energy sources

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CURRENT - The rate of flow of electrons

Measurement

Point

One Coulomb

Per Second

= One Ampere

= One Coulomb

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CURRENT MEASUREMENT

AMMETER

Connected in Series

Circuit Schematic

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VOLTAGE MEASUREMENT

VOLTMETER

VOLTMETER

- Connected in parallel

to measure battery

voltage.

- Connected in parallel

to measure lamp voltage.

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RESISTANCE MEASUREMENT

Measured with

an Ohmmeter

(multimeter used

as an ohmmeter)

Ohmmeters should never

be connected to live circuits!

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Resistors Oppose & Control The Flow of

Current in a Circuit

• Series

• Parallel

• Units: Ohm

• Symbol

• R1, R2, etc schematic

representation

V1

12V

R1

1kohm

R2

1kohm

R3

1kohm

R4

1kohm

V1

12VR1

1kohm

R2

2kohm

R3

3kohm

R4

4kohm

Series

Parallel

R5

1kohm

Symbol

ITI1 I2 I3 I4

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OHM’S LAW FORMULAS

Current equals

voltage divided

by resistance

V = I x R

Voltage equals

current multiplied

by resistance

Resistance equals

voltage divided

by current

Find Current

I = V

RR =V

I

Find Voltage Find Resistance

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VOLTAGE - CURRENT - RESISTANCE

Quantity Unit of Measure

FunctionName NameSymbol Symbol

VoltageV, emf

or EVoltage V

Pressure which

makes current

flow

Current I Ampere ARate of flow

of electrons

Resistance R Ohm Opposition to

current flow

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POWER-The amount of electric energy

converted to another form in

a given length of time.

Power = Voltage x Current

Watts = Volts x Amperes

P = V x I

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Cable Power Loss

P = I 2 x R

P = V x I

= (I x R) x I

= I2 x R

Recall:

V = I x R

Power loss in cable:

P = I2 x RWire

P = power in watts (W)

I = current in amperes (A)

R = resistance in Ohms (Ω)

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ENERGY IS THE ABILITY TO DO WORK

• Energy is measured in Joules or kWh

• Energy is stored in a battery or a gallon of gasoline

• ……..Or stored in water behind a dam

• ……..Or stored in a body in motion

• Energy can be converted from one form to another

• We pay for electricity based on energy used: example $0.10 per kWh

• We buy gasoline by the gallon(126MJ/gallon)

• Power is the RATE at which Energy is transferred or consumed

• Power is measured in Watts or Horsepower

• 1 Watt = 1 Joule/second

• 1Joule = (1Watt) x (1second)

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ENERGY EXAMPLE

Energy = Power x Time

E = (100 W) (300 s)

E = 30,000 J

E = 30 kJ

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ENERGY- Electric energy refers to the

energy of moving electrons

Energy = Power x Time

kWh = kilowatts x hours

Measured with a

kilowatthour

energy meter

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Energy Cost EXAMPLE

Rated for 4.2 kW

Used 20 h/month

Cost of 12¢ per kWh

Energy = Power x Time

= (4.2 kW) x (20 h)

= 84 kWh

Cost = Energy x rate per kWh

= (84 kWh) x ($0.12)

= $10.08

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Series Circuit

• Same current through each component

• Sum of voltage drops = supply voltage (Kirchoff Voltage Law)

• Largest resistance has the

largest voltage drop.

• Add resistance

– Lowers current

• One open the circuit fails.

• The total resistance is the sum of all resistors:

RT = R1 + R2 + R3

I

IT

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SOLVING A SERIES CIRCUIT PROBLEM

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Parallel Resistor Network

R1I1 R2I2 R3I3 RNINVT

IT

From Kirchoff’s Current Law: IT = I1 + I2 + I3 + ------ + IN

From Ohm’s Law: I = V/R and R = V/I

IT =VT

R1

+VT

R2

+VT

R3

+ ---- +VT

RN

=1

R1

+1

R2

+1

R3

+ ---- +RN

1VT

RT = VT / IT = 1R1

+ 1R2

+ 1R3

+ ---- +RN

1

1

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Time for

Lab #1

&

Lab #2

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Troubleshooting

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Troubleshooting

• Series Circuit

– Open:

• No current

• Source voltage at the open

• Rest are zeros

– Short

• Current Increase

• V is zero at the short

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SOLVING A OPEN CIRCUIT

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SOLVING SHORT CIRCUIT

Voltage Current Resistance Power

R1

R2

R3

Total60 V

4 k

2 k

0 (Short)

6 k10 mA

10 mA

10 mA

10 mA

40 V

20 V

0

600 mW

200 mW

400 mW

0 mW

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Troubleshooting

• Parallel

– Short: Fuse blows

– Open: Less current

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Parallel Circuit

• Same Voltage across all components

• Smallest resistance, most current.

• Add a branch:

– Increase Current

– Decrease Overall Resistance

• One branch opens, current is smaller than normal.

• Resistance of Network is less than smallest resistor

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SOLVING A PARALLEL CIRCUIT

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Breaker

opens

Circuit

breaker

closed

Switch

open

EFFECT OF A SHORT CIRCUIT

ACROSS PARALLEL BRANCHES

Switch

closed

Current

jumps to

max value

Voltage

drops

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KIRCHHOFF’S VOLTAGE LAW

VT = V1 + V2 +V3

V1 = 4V V2 = 8V V3 = 12V

VT = 24V

VT - V1 - V2- V3 = 0

+24V - 4V - 8V - 12V = 0

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KIRCHHOFF’S CURRENT LAW

IT = I1 + I2 + I3

IT

(22A) I1(12A)

I2(6A)

I3(4A)

(6A)

(4A)(10A)

IIN = IOUT

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Direct Current

vs..

Alternating Current

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TYPES OF DIRECT CURRENT

Pure or Constant DCPulsating DCVarying or Analog DCDigital DC

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Batteries

• The purpose of a battery is to store chemical

energy and to convert this chemical energy

into electrical energy when the need arises

• Battery safety concerns

– Exposure to chemicals (acid)

– Potential for electrical shock

– Lifting hazard, some batteries in excess of 150 lbs

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Battery Characteristics

• When connecting batteries

in Series you are doubling

the voltage while

maintaining the same

capacity rating (amp hours)

• When connecting in Parallel

you are doubling the

capacity (amp hours) of the

battery while maintaining

the voltage of one of the

individual batteries

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Installing Batteries

• Dependant on battery style, below are the

general rules

– Perform a load test

– Verify condition (physical)

– Service with electrolyte, if required

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AC WAVEFORMS

Sine waveSquare waveSawtooth wave

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GENERATOR PRINCIPLE

Moving conductorMagnetic field

Induced voltage

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CYCLE

One complete wave of alternating current or voltage

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PERIOD

The time required to produce one complete cycle

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FREQUENCY

The number of cycles produced per second

Frequency = Period

1F =

T

1=

0.25 s

1= 4 Hz

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PEAK VALUE

The maximum voltage or current value

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SOLVING AC CIRCUIT RMS

??

I rms = I peak x 0.707

I rms = (10 A) x (0.707)

I rms = 7.07 A

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SOLVING AC PEAK & PEAK-PEAK VALUES

Vpeak = Vrms x 1.414

Vpeak = (120 V) (1.414)

Vpeak = 170 V

Vp-p = Vpeak x 2

Vp-p = (170 V) x (2)

Vp-p = 340 V

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Time for

Lab #3

&

Lab #4

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Common AC Circuit Components

• Resistors

• Capacitors

• Inductors

• Transformers

• AC Power Source

1

1mH

T2IRON_CORE_XFORMER

R5

1kohmR, Resistance in Ohms

C, Capacitance in Farads

L, Inductance in Henry’s

V31V 1000Hz 0Deg

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J4Key = Space

U2

TRIODE_VIRTUAL

X1

CRYSTAL_VIRTUAL

R5

1kohm

L2

Key = a

100mH 5 0%

T1

NLT_VIRTUAL

..

K1

RELAY1AJ11mA 0mA

D2

02BZ2.2

J2

1V 0V

Key = SpaceJ3

5 0%Key = a

100K_LINR2

C3Key = a

100pF 50%

V212V

V31V 1000Hz 0Deg

U1OPTOCOUPLER_VIRTUAL

C20.047Fwww.spacetec.org

1

1mH

FUSES1

D11BH62

1

2

4

3 D31B4B42

Q12N2222A

Q32N3906

Q5FZT705

T2IRON_CORE_XFORMER

LED_blueLED1

Full Wave

Rectifier

Operational

Amplifier

Opto

Coupler

Transformer

Iron Core

Light-

Emitting

Diode(LED)

Electrolytic

CapacitorPotentiometer

Normally

Open

Pushbutton

Switch

Normally

Closed

Pushbutton

Switch

Transformer

Air Gap

NPN

Transistor

PNP

Transistor

Darlington

PNP

Transistor

Alternating

Current

Source

Relay

Current

Controlled

Switch

Zener

Diode

Voltage

Controlled

Switch

Diode

Battery

FuseTriode

Quartz

Crystal

Resistor

Variable

Inductor

Inductor

Variable

Capacitor

Ground

X2100V_100W

Lamp

S2Key = Space

Common Circuit Symbols

IN+

IN-

V S-

V S+

OUT

U3

OPAMP_5T_VIRTUALSingle Pole

Single Throw

Normally Open

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Ohm’s Law

V31V 1000Hz 0Deg

R5

1kohm

1

1mH

I

V

R

C

L

Capacitive Reactance = XC = 1

2fC

Impedance, Z = R2 + ( XL - XC )2

I = V

Z

VC = I • XC

VL = I • XL

VR = I • R

Inductive Reactance = XL = 2fL

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Forward bias current

Forward bias voltage

DIODE CHARACTERISTIC CURVE

0.7 V (silicon)

Reverse bias voltage

Reverse bias current

Reverse breakdownvoltage

Avalanchecurrent

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DIODE LEAD IDENTIFICATION

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Second half cycleCircuit simplified using common ground connections

BRIDGE RECTIFIER

First half cycle

Voltage output

from full-wave

rectifier

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Circuit Protection

• Fuses

• Circuit breakers

• Overload

• Thermal shunt

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OVERLOADED CIRCUIT

Branch circuit

rating:

15 A / 120 V

1500 W

360 W

120 V

3 A

120 W

120 V

1 A

1440 W

120 V

12 A

120 W

120 V

1 A

600 W

120 V

5 A

Total power = 2640 W

Total current = 22 A

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FUSES

Ferrule-contact

cartridge fuse

Knife-blade

cartridge fuse

Glass cartridge fuse Plug fuse

Fuse symbol

OR

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CIRCUIT BREAKERS

Circuit breaker

symbolLight

duty

Heavy

duty

High-voltage

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CURRENT

RATINGS

Plastic automotive

fuse

Household

circuit breaker

20

Rated current

15 Rated

current

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USING AN OHMMETER TO

TEST FUSES

Good

0

Zero resistance reading

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THERMAL OVERLOAD

PROTECTION

Fuse protects

wiring

Thermal

overload switch

protects

motor

Overload = Excessive

temperature

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AUTO STARTER MOTOR CIRCUIT

Starter

motor

Battery

High-current

wiringLow-current

wiring

Electromagnetic Switch

or

Solenoid

Or

Starter Relay

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TRANSISTOR CONTROLLED RELAY

20 mAof controlcurrent

controls10 A of

loadcurrent

Electromagnetic

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RELAY CONTACTS

Single-pole, double-throw

(SPDT)

Double-pole, single-throw

(DPST)

Double-pole, double-throw

(DPDT)

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TYPES

of

CONNECTIONS

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Connections

• High Resistance Connections

• Strip

• Crimp

• Solder (tin lead, 63/37)

• Screw terminal Type

• Heat shrink

• Cable splicing and bending

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NASA Standards for Connections

• NASA Technical Standard 8739.3 “Soldered

Electrical Connections”

• NASA Technical Standard 8739.2 “Workmanship

Standards for Surface Mount Technology”

• NASA Technical Standard 8739.4 “Crimping,

Interconnection Cables, Harnesses, Connectors

• NASA Technical Standard 8739.7 Electrostatic

Discharge

• NASA Technical Standard 8739.5 Fiber Optics

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HIGH-RESISTANCE CONNECTIONS

Loose ConnectionCorroded Connection

Lost Heat Energy

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CONNECTING TO

TERMINAL SCREWS

Bend wire

into a loopHook wire

over the screw

Tighten in

clockwise direction

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CRIMP-ON CONNECTOR

Flattened

Turned inCompressed

The Crimp-on is

also called a

Compression

Connector

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Crimp-Terminal Lugs

Remember:

The size of the connector

Must be matched to the

Wire gauge size

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Crimping Tools Specifications

• Must meet standards set by organization

• ex. NASA-STD-8739.4 section 12.3 states:

– Calibration Intervals based on type of tool and it’s records,

if tool does not perform correctly in between calibration

periods, tool will be sent out for re-calibration

– Indenter blades, tool shall have a minimum of 4

– Ratcheting mechanism will prevent indenter from releasing

before crimp cycle is complete

– Pull tests required for each crimp is a minimum of 3

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Splicing Wires

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Heat Shrink

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Solder

• Solder is an alloy of tin and lead

• Lead/tin ratio determines strength and melting point

• Wire type 60/40 tin/lead is recommended for most electrical/electronic work

• Item being soldered must be cleaned of dirt and oxide…..otherwise solder will not adhere to the splice

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Solder Flux

• Soldering flux prevents oxidation of the copper

surfaces by insulating the surface from air

• Acid and resin based solders are available

• Acid based solder SHOULD NOT be used for

electrical work as it corrodes copper wire

• Resin flux is available in paste form or as a

continuous core inside solder wire and should be used

in electrical work

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Misalign Splices in a Cable

• Splices should be distributed in a cable to

avoid a large bulge in the cable

splice

splice

splice

splice

splice

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SOLDERING TO A TERMINAL

Make a loop

around the

terminal

Bend the wire

through and around

the terminal hole

Apply heat

Apply solder

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CONDUCTOR FORMS

Solid wire

Stranded wire

Large stranded cable

Multiconductor cable

Lamp cord

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AWG WIRE SIZES

The larger the gauge number the smaller

the actual diameter of the conductor.

The primary cable selection criteria are

current rating and allowable voltage drop

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Wiring Color Codes

• Basic Electrical Color Coding

– DC Black –, Red +

– Ac 120v Black Hot, White Neutral, Green Ground,

Red is switched Hot

– Ac 277 3 Phase Black Phase A, Red Phase B, Blue

Phase C, Ground Green

– Ac 480 3 Phase Brown Phase A, Orange Phase B,

Yellow Phase C, Ground Green

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Grounding/Bonding

• Bonding is what is done to prevent you from being shocked/electrocuted when your left hand touches one metal component, and your right hand touches another metal component. By running a wire (bonding wire) from one metal component to another, stray electricity (from a short for example) will equalize through the wire and one metal component will NOT have a greater voltage in it than another metal component

• Grounding is to give stray electrical current a place to go, other than through you.

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Maintain Minimum Cable Bends

• A cable bend radius of at least 10 times the

diameter should be maintained

• True for wire and fiber cable

• Fiber cable can suffer increased attenuation

from too sharp a bend

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Tools

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Tool Pouch

Screwdrivers

Slot

Phillips

Torx

Square

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Basic Tools

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Tools for Connections

Strippers

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Tools for Connections

Crimpers

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Crimp-Terminal Lugs

Remember:

The size of the connector

Must be matched to the

Wire gauge size

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Crimping Tools Specifications

• Must meet standards set by organization

• ex. NASA-STD-8739.4 section 12.3 states:

– Calibration Intervals based on type of tool and it’s records,

if tool does not perform correctly in between calibration

periods, tool will be sent out for re-calibration

– Indenter blades, tool shall have a minimum of 4

– Ratcheting mechanism will prevent indenter from releasing

before crimp cycle is complete

– Pull tests required for each crimp is a minimum of 3

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Wire Benders

• NASA –STD – 8739.3

Section 8.1.6.d states

any wire bending tools

shall not show evidence

of nicks or deformations

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Digital Circuits

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CHAPTER 41

DIGITAL FUNDAMENTALS

The world is moving from the

industrial revolution to an information

and communications revolution based

on digital electronics.

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CHAPTER 41

DIGITAL FUNDAMENTALS

This chapter serves as an introduction

to digital technology. It focuses on the

devices and circuits used to build

computers and other digital

equipment.

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DIGITAL SIGNAL

WAVEFORMS

All voltages

above this

level are considered

to be ON (1)

All voltages

below this

level are considered

to be OFF (0)

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BINARY DATAUSING SWITCHES TO ENTER BINARY DATAUSING LEDs TO READ OR

DISPLAY BINARY DATA

16-BIT WORD MADE UP OF TWO BYTES

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THE AND GATE

LOGICAL AND

THREE-INPUT AND GATE

Automotive application

PULSED GATE OPERATION

CIRCUIT SCHEMATIC

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THE OR GATE

THE LOGIC OR

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THE NOT (INVERTER) GATE

THE LOGICAL NOT

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THE NAND GATE

Timing diagram

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THE NOR GATE

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DIGITAL SIGNAL CODING

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COMBINATION LOGIC CIRCUIT

0 0 0 0

0 0 01

00 01

00 1 1

00 01

01 1 1

01 1 1

1 1 1 1

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EXCLUSIVE-OR (XOR) FUNCTION

USED FOR THE COMPARISON OF TWO BINARY NUMBERS

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ANALOG-TO-DIGITAL CONVERSION

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DIGITAL-TO-ANALOG CONVERSION

SampleBinaryInput

DC analogvoltage output

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DIGITAL LOGIC PROBE

CIRCUIT CONNECTIONS

TESTING A GATE

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This Concludes Applied Basic Electricity

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BACK UP SLIDES

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APPLYING DC VOLTAGE TO A COIL

Magnetic field

builds up

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REMOVING THE DC VOLTAGE

Magnetic field

collapses

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MUTUAL INDUCTANCE

Switch operatedon and off

Changing magneticfield created

Voltageproduced

Φ = MMF/R

MMF = Magneto

Motive Force

In Amp-Turns

R = Reluctance

Φ = Flux

V = N d Φdt

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EXAMPLE 30-4

XL = ?

XL = 2fL

= (2) (3.14) (1000 Hz) (0.2 H)

= 1,256

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IDEAL TRANSFORMER

Power in = Power out

V x I primary = V x I secondary

(120 V) (0.625 A) = (15 V) x (5 A)

75 VA = 75 VA

The basis for

transformer

operation is

mutual

inductance

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EXAMPLE 31-2

VS = 2 x 120 V = 240 V

Turns ratio =NP

NS

= 1:2=50

100

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EXAMPLE 31-3

240 V20

VS = = 12 V

Turns ratio =NS

NP= = 20:1

100

5

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EXAMPLE 31-4

60 V

25

= 2.4 A

IP = 5 x IS

= 5 x 2.4 A

= 12 A

IS =

=

VS

RL