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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