DAY1 BASIC ELECTRICAL CONCEPTS CONSTRUCTION 275

ELECTRICAL UNITS AND SYMBOLS

QUANTITY UNIT SYMBOL

CURRENT AMPERE(A) I

VOLTAGE VOLT(V) V

RESISTANCE OHM(Ω) R

FREQUENCY HERTZ(Hz) f

POWER WATTS(W) P

ELECTRICAL QUANTITIES AND UNITS

COULOMB: BASE UNIT OF CHARGE= ELECTRONSCHARGE SYMBOL =QABBREVIATION =C

ELECTRIC CURRENT (I): MOVEMENT OF CHARGED PARTICLES IN A SPECIFY DIRECTION CAN BE +OR-.

181025.6

CURRENT= Q/t CHARGE/TIME

AMPERE ONE COULOMB/SEC OR ELECTRONS/ SEC

181025.6

sCA 11

Basic Electricity - What is an amp? http://www.youtube.com/watch?v=8gvJzrjwjds

http://www.youtube.com/watch?v=sSVI5l-MbMQ&list=UU2bkHVIDjXS7sgrgjFtzOXQ

Copper: The Miracle Metal

CURRENT THAT IS FLOWING IN THE SAME DIRECTION ALL THE TIME IS KNOWN AS DIRECT CURRENT

SYMBOL I WAS CHOSEN FOR CURRENT BECAUSE IT WAS THOUGH TO REPRESENT THE INTENSITY OF ELECTRICITY IN A WIRE. CURRENT MOVES AT LESS THAN THE SPEED OF LIGHT IN ANY WIRE.

UNIT OF VOLTAGE (V) IS THE VOLT.

VOLTAGE=EMF(ELCTROMOTIVE FORCE)=POTENTIAL DIFFERENCE

POLARITY: HELPS TO INDICATE WHICH DIRECTION CURRENT IS FLOWING. CAN BE + OR -

WHEN TERMINALS ARE IDENTIFIED ON A ELECTRONIC DEVICE, IT IS SAID TO BE POLARIZED.

POLARITY MUST BE CORRECT FOR THE DEVICE TO WORK. IF THE DEVICE IS CONNECTED BACKWARD, IT IS SAID TO BE IN A STATE OF REVERSE POLARITY AND NO CURRENT WILL FLOW.

SOURCES OF VOLTAGE

REMEMBER ONE FORM OF ENERGY MUST BE CONVERTED FROM ONE FORM TO ANOTHER TO CREATE VOLTAGE.EXAMPLES:POWER PLANT GENERATORS

COAL

NUCLEAR

HYDROELECTRIC

CONVERT MECHANICAL ENERGY INTOELECTRICAL ENERGY

SOLAR

GEOTHERMAL

RESISTANCE:OPPOSITION TO CURRENT FLOW IN A MATERIAL. ELECTRICAL ENERGY IS CONVERTED INTO HEAT.

CONDUCTORS: OFFER LITTLE RESISTANCE TO CURRENT FLOW. WHY? DO TO THE EASE AS WHICH VALANCE ELECTRONS CAN BE RELEASED FROM THE OUTER SHELL OF AN ATOM.GOOD CONDUCTORS: SILVER,GOLD,ALUMINUM,COPPER.BAD CONDUCTORS: RUBBER,WOOD,CERAMIC MATERIAL, GLASS

INSULATORS HAVE HIGH RESISTANCE TO CURRENT FLOW.

A BAD CONDUCTOR IS A GOOD INSULATOR.

MOST INSULATORS ARE COMPOUNDS OF TWO OR MORE ELEMENTS. THEY SHARE ELECTRONS BY COVALENT BONDING.(MAKES IT HARDER FOR ELECTRONS TO BE FREED.) LIKE THESE GLASS AND CERAMIC INSULATORS.

UNIT OF RESISTANCE THE OHM. Ω

4 FACTORS THAT EFFECT RESISTANCE 1. TYPE OF MATERIAL 2. LENGTH OF OBJECT 3. CROSS SECTIONAL AREA 4. TEMPERATURE OF OBJECT

Make presents ohm’s law http://blog.makezine.com/2009/12/23/make-presents-ohms-law/

POWER/ENERGY: ABILITY TO DO WORK, GAUGE OF HOW ENERGY IS CONVERTEDFROM ONE FORM TO ANOTHER.POWER CAN ALSO BE THOUGHT OF AS THE RATE OF USING ENERGY OR WORK.

FOR 100%EFFICIENCY, Pout =Pin, NOT POSSIBLE!!VIOLATES THE LAWS OF THEMODYNAMICS

100

%100

xE

EEFFICIENCY

xPower

PowerEFFICIENCY

in

out

input

output

SIX PARTS OF AN ELECTRIC CIRCUIT

1.ENERGY SOURCE: VOLTAGE SOURCE: TO CREATE ELECTRIC FIELD WHICH STARTS CURRENT FLOW2.CONDUCTORS: PATHWAY FOR CURRENT TO FLOW.3.INSULATORS: PREVENTS CURRENT FROM GOING WHERE WE DON’T WANT IT TO.4.LOAD : PLACE WHERE CURRENT CAN BE CONTROLLED AND CONVERTED FOR ITS INTENDED USE.5.CONTROL DEVICE:SWITCH TO TURN THE CURRENT ON/OFF.6.PROTECTION DEVICE: STOPS CURRENT FLOW IF OVERLOAD OCCURS(USUALLY A SHORT CIRCUIT.)

FIRST 4 PARTS ARE ESSENTIAL, LAST 2 ARE OPTIONAL.

EXAMPLE OF A SIMPLE CIRCUIT, FLASHLIGHTHAS LOAD,VOLTAGE SOURCE, AND CONTROL DEVICE.

FLASHLIGHT CASE IS PART OF THE CONDUCTIVE PATH. ARROWHEAD INDICATES DIRECTION OF CURRENT FLOW.

MEASURING ELECTRICAL QUANTITIES

• VOLTAGE: VOLTMETER

• CURRENT: AMMETER

• RESISTANCE: OHMMETER

• POWER: WATTMETER

MULTIMETER:COMBO OF VOLTMETER,AMPMETER AND OHMMETER.

TWO TYPES, DIGITAL AND ANALOG

Make Magazine: the multimeter http://www.youtube.com/watch?v=BW3Wj7UD-_s

ANALOG MULTIMETER:VOM(VOLT-OHM- MILLIAMETER)

• HAVE FUNCTIONS:WHAT QUANTITY IS BEING MEASURED.• HAVE RANGES: AMOUNT OF QUANTITY BEING MEASURED.

• HAVE SCALES: DEPENDS ON FUNCTION AND RANGE THAT METER IS SET TO.

VOM HAVE 5 FUNCTIONS.

1 AC VOLTAGE

2 DC VOLTAGE

3 DC CURRENT

4 RESISTANCE

5 CONTINUITY

OHM SCALE: DIFFERENT FROM OTHER SCALES

1. REVERSE READING

2. NONLINEAR

3. DIVISON OF SCALES IS NONLINEAR.

DIGITAL MULTIMETERS NO SCALES,BETTER ONES HAVE AUTORANGING

TESTING CONTINUITY

MEASURING RESISTANCE

ON VOM:TOUCH TEST LEADS TOGETHER,USE ZERO OHM KNOB TO SET TO ZERO, MUST BE REPEATED FOR EACH SCALE.

THE OHMMETER FUNCTION HAS ITS OWN POWER SOURCE (INTERNAL BATTERY) TO ALLOW RESISTANCE MEASUREMENTS.

DON’T TOUCH METAL PARTS OF TEST LEADS WHEN MAKING MEASURMENTS.

MEASURING VOLTAGE: POWER IS CONNECTED TO THE CIRCUIT.

MEASURING CURRENT: MUST INSERT METER INTO CIRCUIT PATH TO WORK

AMMETER CAN BE DAMAGED IF USED INNCORRECTLY.(LIKE A VOLTAGE METER)

MEASURING VOLTAGE: POWER IS CONNECTED TO THE CIRCUIT.

MEASURING VOLTAGE ACROSS LAMP2.

MEASURING CURRENT: MUST INSERT METER INTO CIRCUIT PATH TO WORKAMMETER CAN BE DAMAGED IF USED INNCORRECTLY.(AGAIN IF USED LIKE A VOLTAGE METER)

WIRE,CABLES

WIRE IS A SINGLE CONDUCTOR (INSULATED OR NON INSULATED)

CABLE HAS MULTIPLE CONDUCTORS

CONDUCTORS CAN BE SOLID OR STRANDED

SOLID COPPER CONDUCTOR COVEREDWITH INSULATION

AWG gauges are also used to describe stranded wire. In this case, it describes a wire which is equal in cross-sectional area to the total of all the cross-sectional areas of the individual strands; the gaps between strands are not counted. When made with circular strands these gaps occupy about 10% of the wire area, thus requiring a wire about 5% thicker than equivalent solid wire.Stranded wires are specified with three numbers, the overall AWG size, the number of strands, and the AWG size of a strand. The number of strands and the AWG of a strand are separated by a slash. For example, a 22 AWG 7/30 stranded wire is a 22 AWG wire made from seven strands of 30 AWG wire.

Increasing gauge numbers give decreasing wire diameters, This gauge system originated in the number of drawing operations used to produce a given gauge of wire. Very fine wire (for example, 30 gauge) required more passes through the drawing dies than did 0 gauge wire. The AWG tables are for a single, solid, round conductor. The AWG of a stranded wire is determined by the total cross-sectional area of the conductor, which determines its current-carrying capacity and electrical resistance. Because there are also small gaps between the strands, a stranded wire will always have a slightly larger overall diameter than a solid wire with the same AWG.

STRANDED CONDUCTORS

MANY WIRES TWISTED TOGETHER, MORE FLEXIBLE THEN SOLID WIRE.

SMALLER WIRES ARE OFTEN COATED WITH A THIN LAYER OR SOLDER, SINCE BARE COPPER OXIDIZES EASILY.

YOU TUBE: Cable Basics 101: Conductors

http://www.youtube.com/watch?v=gtAaZ2hFYTA

MULTIPLE LOAD CIRCUITS

IF YOU HAVE TWO OR MORE LOADS, THEY CAN BE CONSTRUCTED IN SERIES, PARALLEL OR SERIES-PARALLEL.

SERIES CIRCUITS: ONE PATH FOR CIRCUIT FLOW.

CURRENT IS THE SAME IN EACH ELEMENT: IT=I1=I2=I3

R1

R3

R2

IT

VT

-

-

-

-

+

+

+

+

IN SERIES CIRCUITS CURRENT IS THE SAME IN EACH ELEMENT.

SO 321 IIIIT

AN AMPERE METER PLACED AT ANY POINT IN THE CIRCUIT WILL GIVE THE SAME CURRENT READING.

RESISTANCE IN A SERIES CIRCUIT, ADD TOGETHER FOR THE TOTAL RESISTANCE.

NT RRRRR ....321

R1

R3

R2

IT

VT

VOLTAGE IN SERIES CIRCUITS

VOLTAGE IS DIVIDED UP ACROSS EACH LOAD. 321 VVVVT

30V

10V

10V

10V

FINDING A OPEN IN A SERIES CIRCUITS

IF ANY PART OF THE CIRCUIT IS OPEN,CURRENT STOPS,VOLTAGE,POWER ARE REMOVED FROM ALL THE LOADS.

0V

0V

12 VV

V

V

R2

R1

R3

0VR2

FINDING SHORTS IN SERIES CIRCUITS: WHEN ONE LOAD IS SHORTED OUT, OTHERS MAY CONTINUE TO OPERATE.

IN THIS EXAMPLE WHEN L2 IS SHORTED, THE OTHER LAMPS CURRENT AND VOLTAGE INCREASE 50%. THE INCREASED POWERTO THE LAMPS WILL LIKELY BURN THEM OUT.

SHORT

1A

10V,10W

L1

30V L2

L3

10V,10W

10V,10W

1.5A

15V,25W

L1

30V L2

L3

0V,0W

15V,25W

PARALLEL CIRCUITS

IS A MULTILOAD CIRCUIT WITH MORE THEN ONE CURRENT PATH. EACH PATH IS CALLED A BRANCH.

EACH BRANCH HAS ITS OWN LOAD. TOTAL CURRENT IS SPLIT ACROSS EACH BRANCH. EACH BRANCH IS INDEPENDENT OF THE OTHERS.

V R1 R2 R3

IT

I1 I2 I3

IF A BREAK IN CURRENT FLOWOCCURS IN A SERIES CIRCUITLIGHTS GO OUT!

IN A PARALLEL CIRCUIT, IF ONE BRANCHIS CUT OFF.THE OTHER BRANCH STILLWORKS AND THE LAMP GLOWS.

SERIES-PARALLEL CIRCUIT

ELECTROMAGNETISM

A MOVING ELECTRIC CURRENT CREATES A MAGNETIC FIELD WHICH IS PERPENDICULAR TO THE CURRENT FLOW.

Field strength is directly proportional to the amount of current flowingthru the conductor. If the current doubles, the field strength doubles.

FORCE BETWEEN CONDUCTORSTWO PARALLEL CURENT CONDUCTOTS ATTRACH EACH OTHER IF THE CURRENTS ARE FLOWING IN THE SAME DIRECTION. THERE FIELD LINES JOIN TOGETHER. THE OPPOSITE OCCURS IF CURRENTS ARE TRAVELING IN THE OPPOSITE DIRECTION

REPEL EACH OTHER

ATTRACH EACH OTHER

XXX

MAGNETISM

MAGNETISM IS A FORCE THAT ACTS ON CERTAIN MATERIALS.

WHAT MATERIALS? ALLOYS OF COPPER,NICKEL ALUMINIUM, IRON, COBALT.

THIS MAGNETIC FORCE IS REFERRED TO AS A MAGNETIC FIELD. THE FIELD EXTENDS OUT FROM THE MAGNETIC MATERIAL IN ALL DIRECTIONS.

LINES OF FORCE OF A MAGNETIC FIELD ARE KNOW AS MAGNETIC FLUX (Φ)

FLUX IS STRONGER WHERE LINES OF FORCE ARE CLOSER.

FLUX IS WEAKER WHERE LINES OF FORCE ARE FATHER APART.

FLUX IS ALWAYS STRONGEST AT THE END OF A MAGNET.

LINES OF FORCE LEAVE THE N POLE AND ENTER THE S POLE.

AS WITH ELECTRIC CHARGES, LIKE MAGNETIC POLES REPEL EACH OTHER, UNLIKE MAGNETIC POLES ATTRACT EACH OTHER.

COILS

IF A CURRENT CARRYING WIRE IS TIGHTLY WOUND INTO A COIL, A ELECTROMAGNET IS CREATED.

STEP UP/DOWN TRANSFORMERS

SIMPLE TRANFORMER WHEN A CURENT CARRYING WIRE IS WRAPED AROUND A IRON CORE( PRIMARY WINDING) IT WILL INDUCE A MAGNETIC FLUX IN THE IRON CORE.IF A SEPARATE SECOND COIL IS WRAPED AROUND THE CORE(SECONDARY WINDING) ACURRENT WILL BE INDUCED IN THIS WIRE.

SOLENOIDSAN ELECTROMAGNETIC DEVICE THAT ALLOWS A ELECTRIC CIRCUIT TO CONTROL A MECHANCIAL DEVICE.( VIA A PLUNGER)

HOW DOOR CHIMES WORK

A relay is an electrical switch that can be opened or closed by an electrical signal. It is an electrically controlled switch. People use them when they want a small amount of electricity to control a bigger amount of electricity. The same thing can be done with transistors, but transistors can't handle the amount of current that relays can.

RELAYS

AC AND VOLTAGE

FOR A DC WAVEFORM IN A SIMPLE CIRCUIT THE OUPUT IS ALWAYS CONSTANT, EXCEPT WHENTHE CIRCUIT IS SWITCHED ON/OFF. DC WAVE FORMS CAN BE + OR - BUT NEVER BOTH.

CYCLE : ONE WAVEFORM THAT DOES NOT REPEAT ITSELF.

½ CYCLE

PERIOD (T) : TIME TO COMPLETE ONE CYCLE.( IN THIS CASE .25 SECONDS).

.25 S

FREQUENCY( f ) : # OF CYCLES/SECOND

Time (sec) FOR THIS WAVEFORM f = 1 CYCLES/SEC

HERTZ: UNIT OF FREQUENCY . FOR THE ABOVE WAVEFORM f = 1 Hz

AMPLITUDE: HEIGHT OF THE WAVEFORM.

RMS value is an equivalent DC value which tells you how many volts or amps of DC that a time-varying sinusoidal waveform is equal to in terms of its ability to produce the same power. For example, If you have mains supply of 240Vac and is assumed an effective value of “240 Volts RMS”. This means then that the sinusoidal RMS voltage from the wall sockets of a home is capable of producing the same average positive power as 240 volts of steady DC voltage as shown below.

1. AC CAN BE GENERATED AT HIGH VOLTAGES.2. HV AC GENERATORS ARE SIMPLER AND CHEAPER THEN DC

GENERATORS.3. AC CAN BE STEPPED UP OR DOWN WITH TRANSFORMERS.

ACTUAL VOLTAGES COULD BE MEASURED AS 110V,115, 118V,125V, ETC.NOMINAL VOLTAGE MEANS IN NAME ONLY, NOT A FACT.( USE OF 120V)

ADVANTAGES OF A.C. OVER D.C. / WHY GENERATION IS DONE IN A.C.

20KV500A10 MW

STEP UP TRANSFORMERAT POWER PLANT

400KV25A10 MW

LONG DISTANCETRANSMISSION LINES

400KV25A

20KV500A10 MW

STEP DOWN DISTRIBUTIONTRANSFORMER AT SUBSTATION

TO LOADS AND OTHERSTEP DOWNTRANSFORMERS.

ADVANTAGES OF HIGH VOLTAGE TRANSMISSION LINES

50Hz vs. 60Hz

UTILITY FREQUENCIES IN USE IN 1897 IN NORTH AMERICA

Hz Description

140 Wood arc-lighting dynamo

133 Stanley-Kelly Company

125 General Electric single-phase

66.7 Stanley-Kelly company

62.5 General Electric "monocyclic"

60 Many manufacturers, becoming "increasingly common" in 1897

58.3 General Electric Lachine Rapids

40 General Electric

33 General Electric at Portland Oregon for rotary converters

27 Crocker-Wheeler for calcium carbide furnaces

25 Westinghouse Niagara Falls 2-phase - for operating motors

3 PHASE AC: POWER PLANTS PRODUCE 3 PHASE AC. EACH PHASE IS SEPARATED BY 120°.

3 PHASES ARE CONNECTED SO THE LOAD CAN BE CARRIED ON 3 CONDUCTORS FROM THE POWER PLANT TO THE USER.3 PHASES ARE CONNECTED IN EITHER DELTA OR WYE CONFIGURATION.

GROUND

NEUTRAL

LINE 1

LINE 2

LINE 3

PHASE 1 120 V

PHASE 2 120 V

PHASE 3 120 V

120 V

120 V

120 V 208 V

208 V

208 V

3 PHASE 120 V/208V 4 WIRE WYE SYSTEM

TO 3 PHASE LOADS

UNDER LOAD:LINE AND PHASE CURRENTS ARE NOT EQUAL.SINCE 2 PHASE VOLTAGES ARE SEPARATED BY 120º , THEY CANNOT BE ADDED TOGETHERILINE = 1.732IPHASE

VLINE = 1.732VPHASE

VLINE2 = 1.732(120V) = 208VSINGLE PHASE 120 V ARE CONNECTED BETWEEN THE NEUTRAL AND ANY LINE.SINGLE PHASE 208 V CIRCUITS ARE CONNECTED BETWEEN ANY 2 OF THE 3 LINES.3 PHASE 208 V ARE CONNECTED ACROSS 3LINES.

BATTERIES,CELLS ARE POWER SOURCES.

CELLS: MADE FROM TWO ELECTRODES,TWO DIFFERENT METALS AND A ELECTROLYTE. CHEMICIAL REACTION BETWEEN THE 3 PRODUCE ELECTRIC.

BATTERY: TWO OR MORE CELLS.

CELL

BATTERY

TWO TYPES OF CELLS

PRIMARY: NOT RECHARGABLE

SECONDARY :RECHARGABLE, # OF CYCLES VARIES FROM 100’S TO1000’S.

WET CELL: USED IN UPRIGHT POSITION TO PREVENT ELECTROLYTE LEAKAGE.

MUST BE VENTED, FOR OUTGASING.

DRY CELL: OPERATE IN ANY POSITION WITHOUT LEAKAGE.

BATTERY CELL RATINGS:AMOUNT OF ENERGY CELL CAN PROVIDE UNDER CERTAIN CONDITIONS.

DEPENDS ON: TEMPERATURE,CURRENT DRAIN, DISCHARGE RATE.

CELL/BATTERY CAPACITY IS EXPRESSED IN AMPERE-HOURS (Ah)

LEAD ACID CELL: PRODUCE ABOUT 2.1V/CELL. 12V CAR BATTERY WITH 6 CELLS PRODUCES 12.6 V. WHEN STARTING A CAR 12.6V DROPS TO ABOUT 8V,WHY? AS V DECREASES, INTERNAL RESISTANCE INCREASES PRODUCING IR VOLTAGE DROP.

BATTERIES

THERE IS A POTENTIAL ENERGY DIFFERENT BETWEEN THE + AND – TERMINALS OF THE BATTERY. WHEN CURRENT FLOWS WORK IS DONE. POTENTIAL ENERGY . IS CONVERTED INTO ANOTHER FORM OF ENERGY, IN THIS CASE AS HEAT IN THE RESISTOR.

BATTERY IS DISCHARGING BATTERY IS CHARGING

DIRECTION OF ELECTRON FLOW ELCTRON FLOW IS REVERSED

+

־+

־

RECHARGING

LEAD-ACID BATTERIES ARE RECHARGED BY FORCING A REVERSE CURRENT (AT A HIGHER VOLTAGE THEN THE BATTERY RATING) THRU THE CELL.

SPECIFIC GRAVITY: RATIO OF THE WEIGHT OF A SUBSTANCE TO THAT OF WATER.

EXAMPLE: S.G. OF 1.251 IS 1.251 TIMES HEAVIER THEN WATER.

S.G. INDICATES THE STATE OF CHARGE OF THE BATTERY.

HYDROMETER: USED TO MEASURE THE S. G. OF A LEAD-ACID BATTERY.

A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used. Fuel cells are different from batteries in that they require a constant source of fuel and oxygen/air to sustain the chemical reaction, they can however produce electricity continually for as long as these inputs are supplied.

FULL CELLS

The portable JENNY 600S provides power directly to electrical devices or recharges secondary batteries. The small fuel cartridges contain 0.35l of methanol with a charging capacity of 400Wh each, equaling 2.2 BA-5590 batteries and saving you up to 80% weight.

MAN PORTABLE FUEL CELL

SOLDERING

30 WATT SOLDERING IRON 80 WATT SOLDERING STATION

300 WATT SOLDERING IRON

KESTER 44 SOLDER

60% TIN/40% LEAD

WIRES STRIPED

WIRES TWISTED TOGETHER

WESTERN ELECTRIC WIRE SPLICE

TINNING IRON

REMOVING EXCESS SOLDER

HEATING WIRE PRIOR TO SOLDERING

SOLDERING TWISTED PAIR WIRE

FINISHING THE JOB WITH HEATSHRINK TUBING

JOB#12

http://www.youtube.com/watch?v=x8ekfxijhuA&list=UUOc3q8ChcDYyeyFROxLDhuw

Knob and Tube - early electrical insulation