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Electrical FundamentalsSequence 1
Basic Installation
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ACKNOWLEDGEMENTS
Wewouldliketothankthefollowingcompaniesfortheuseofphotographsand
othermaterialsusedinthispresentation.
ABYCBlueSeasSystems CrusairAirConditioning
CumminsMarineEngines EdShermanFURUNOUSA HubbellPowerSystemsIdealWindlasses ITTJabsco
Marinco NorthernLightsGenerators OnanGenerators Raritan SeawardProducts SidepowerThrusters Xantrex
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Electrical Fundamentals
TOTAL COURSE HOURS=80CLASS HOURS=48 LAB HOURS=32
Course Description:Thesuccessfulstudentwillunderstandelectricalprinciplesastheyapplytocircuitandelectricaldesignandwillbeproficientintheuseofelectricalmetersand
testequipmentusedbycontemporarymarineelectricaltechnicians.Thestudentshouldbeabletodemonstrateproficiencyintroubleshootingcommonelectricalcircuitproblems,suchasshorted,opencircuit,highresistancecircuitsandfindingfaultycomponents.ThestudentwillbeintroducedtotheelectricalstandardsassetforthbytheABYCandhowtoapplythestandardsinserviceandinstallationwork.Location: IYRSCampus,RestorationHall 449ThamesStreet
Newport,RI02840 401-848-5777Times and Dates:TuesdayandThursdaynights,6-9pm;OneSaturday,9am4pm???
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Instructor:GeoffAlmeidaOffice:401-848-5777;Cell:401-207-4005;email:[email protected]
Grading criteria:Classparticipation 30%Quizzes 10%LabParticipation 30%Homeassignments 30%Attendanceismandatory.
Text and tools required: IYRSwillprovidetextandsometools. Astandardwrenchset,andadjustablewrenchand/oraverybasictoolkitwouldbehelpful.
Thereisnoprerequisiteforthiscourse.
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OPENING STATEMENT
Electricityatfirstwasusedtomerelystarttheengineandrunsomelights.
Itsnowanessentialpartof
mostboats.
Itscommonlyusedformostpumps,alllights,navigation,refrigeration,heating,entertainment,thrusters,winches,younameit.
Itsamajorshareofonboardsystems,largepartofboatbuildingandaverycommontypeofrepairinboatyards-alongwithfiberglassandmechanical.
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SHOP SAFETY
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THREE SOURCES OF POWER1. BATTERIES
OnboardstorageofDCpower.Mostmarinegearrunsofftheshipsbatteries.2. SHORE POWER
120Vand240V(sameasinahome). Forlargerloadssuchasrefrigeration,airconditioning.Alsotojustchargebatterieswhenatadock.
3. ON BOARD GENERATION
Alternator(enginedriven)tochargebatteriesandtofurnishpowertoengineaswell.
WindorsolargenerationofDCtorechargebatteries. GeneratordevelopsACcurrent(120V&240V),whichcanbeusedforAirConditioning,stoves,heaters,batterychargers,oranyappliancenormallyseeninthehome.
InverterscreateACfromDCusingshipsbatteries.
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Types of Electrical Power
DC Power - Direct CurrentMostoftheboatrunsoffDC.oRequiredforengines
oPolarity-basedsystemoVerysafe
AC Power - Alternating Current Commonlyusedfortypicalhousehold-typeappliances.
CanbeconvertedtoDCwithdiodesorbyplugginginabatterycharger.
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AC VERSUS DCDC - Pros
DCconstantvoltageflowinginonedirection.Ifseenonscope,2parallellines,onebeing0v,theother12,24,etc.
Easilystoredinbatteries.
Easilygeneratedforrechargingofbatteriesbyanenginealternator,solarorwindpowerorbyanAC-poweredbatterycharger.
Relativelylowvoltagehaslowshockrisks
Capableoffairlyhighpowerapplications(highwattage)suchasenginestart,windlass,thruster.
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DC - Cons
Whenveryhighwattagerequired,becausevoltsarelow,ampsveryhighV x A = W
Therefore,forsomethingslikeairconditioningwhere3+KWarerequired,ampsmaybe250ormoreat12VDCbutonly26atAC.
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AC - ProsWhenveryhighwattagerequired,becausevoltsarehigh,ampsarelow.
VxA=W
Thereforeforsomethingslikeairconditioningwhere3+KWarerequired,ampswouldbemaybe250ormoreat12VDCbutonly26at115AC.
Becauseampsarelower,smallerwireisrequired.
ACtravelsfurtheronlargevessels.
ItmakessensetorunACforrunninglightsandothertypesofgearwhen
runsarein100soffeet. ACvoltagecanbesteppedupordowntomake220Vfrom110,or110from220.
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AC - Cons
Shockhazardinwetenvironmentsgroundingandinsulationveryimportant.
Cantbestored,somustrungensetwhenunderway,orrunaninverter.ButinverterusesDCat10timestheamphours.
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POWERVOLTS AMPS WATTS
Where:V = volts = difference in potential (pressure)Amps = current = charged particles = rate of flow
Watts = power = volts x amps
Definepower-theoldplumbinganalogy.
PowerrequirementscandetermineDCandACsystemvoltages.
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The Power Equation
TosolveforWmultiplyVxATosolveforVorAdivideWbyknownfactor
WV A
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RESISTANCEOHMS LAW
OhmsLawandtheplumbingresistanceanalogyhttp://www.grc.nasa.gov/WWW/K-12/Sample_Projects/Ohms_Law/ohmslaw.html
V= I x R
Where:V=volts=differenceinpotential I=current=amps=chargedparticles=rateofflow R=Resistance=Resistanceistheoppositionthatamaterialbodyoffers tothepassageofanelectriccurrent.
ResistanceismeasuredinOhms.
http://www.grc.nasa.gov/WWW/K-12/Sample_Projects/Ohms_Law/ohmslaw.htmlhttp://www.grc.nasa.gov/WWW/K-12/Sample_Projects/Ohms_Law/ohmslaw.htmlhttp://www.grc.nasa.gov/WWW/K-12/Sample_Projects/Ohms_Law/ohmslaw.html -
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In General,
Withagivenresistance,increasevoltage,andampsincrease
Ifresistanceincreases,andvoltagestaysthesame,ampsgodown
Inallcircuits,resistancecausesvoltagedrop(loss)asitpasses
throughcircuit Measuringvoltagedropacrosssolenoid
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TosolveforVmultiplyIxRTosolveforIorRdivideVbyknownelement
VI R
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EXAMPLES OF HOW RESISTANCE WILL MESS YOU UP
Wire gaugesThesmallerthewiresize,themoreresistancetocurrentflow.Ifwelettheresistorinthepreviousfigurerepresentwireresistance,wecancalculatethevoltagedropincurredinthecircuit.OrwecanusetheABYCtablesfordeterminingwiresizesforthispurpose.
Loose connectorsThereisverylittlecontactareabetweenthewireandterminalorbetweentheterminalandthelug,etc.Resistancebecomesveryhighandiftheloaddemandshighwattage,theampsgowayupbecauseresistanceiscausingalargevoltagedrop.Ihaveseenfirescausedbythisinwindlassandstartercircuits.
Corroded terminals, wires or other connections:Sameaslooseconnectorastheresistanceishighduetopoorconductivityandthereforethereisalargevoltagedrop.Dimmingoflights,pumpsrunslowly,electronicsshutdownfromlowvoltage,andpoorperformanceofelectricalgearingeneral.Ihaveseenfirescausedbythisinshorepowerinletsandatpanelfeedcircuits.
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Poor feeds to distribution points:Toosmallawiresizeortoomanyloadshavebeenaddedtopositivepointoffeedornegativebuss.
General under sizing of distribution system:
Dimmingoflights,pumpsrunslowly,electronicsshutdownfromlowvoltage,poorperformanceofelectricalgearingeneral.
Poor engine starting:Especiallyincoldweather,alsowhenenginesarehardstartingforotherreasonsaswell.
Poor charging characteristics:
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DCDirect currentDC=constantvoltageflowinginonedirection.Ifseenonscope,2parallel
lines,onebeing0V,theother12,24,32.etc.
Producedandstoredinbatteries.
Electronstravelinalooporcircuit.Theywillnotflowuntilcircuitorswitchis
closedtoformfeedandreturnpathtobattery
Otherthanaudio,RF,orhighvoltagecircuits,mostdevicesconsistofDCtypecircuitsandcomponents.
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BASIC PARTS OF A DC CIRCUIT INCLUDE:
Battery
Batteryswitch
Overcurrentprotection
Wire
Load
Return
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ELECTRICAL CURCUITS
DirectCurrent(DC)isonethatflowsalwaysinthesamedirection.
Most electronic devices need DC because they require a steady flow ofelectrons that always head in the same direction. A battery is DC.Alternating Current (AC) is changed DC with the use of diode rectifiers.
You cannot use a transformer with DC.
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PARALLEL CIRCUITSLoadsforlights,etc.-constantvoltagebecausethereisnoresistance
fromloadtoload.
ParallelCircuit
Parallelcircuitsarethoseinwhichthecomponentsaresoarrangedthatthecurrentdividesbetweenthem.Inparallelcircuits,thevoltageremainsthesamebutthecurrentmayvary.Thecircuitsinyourhomearewiredinparallel.
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Resistance and voltages within a parallel circuit
Totalresistancelessthanlowestresistor
Voltagedropacrosseachresistorthesame
Ampsthrougheachresistordifferentbasedonresistance
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Exercise:1 = 1 + 1 + 1 Rt R1 R2 R3
Therefore:1/500+1/500+1/1000=1/Rt
.002+.002+.001=1/.005=200 totalSo,12V200=.06 Amps total
Lets Check it
R1:12V500= .024Amps
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R2: 12V500= .024Amps
R3: 12V1000= .012Amps
.06 Amps Total Cool, eh?
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SERIES CIRCUITForsensorsandalarms
Series Circuit
R1 R2
R3
Aseriescircuitisoneinwhichallcomponentsareconnectedinachain.The
currentateverypointofaseriescircuitstaysthesame.Inseriescircuits,thecurrentremainsthesamebutthevoltagedropsvary.
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Resistances and voltage within series circuitTotalresistanceequalssumofallloadsinseriesRt = R1 + R2 + R3
Ampdrawsameanywhereincircuit Voltagewillbedifferentthroughoutcircuit
oUseohmslawtocalculatevoltagebasedonampsandresistanceExercise:Totalresistance=500+500+1000=2000
Totalamps=12V2000=.006AMPSAtR1:.006AmpsX500=3Vdrop
R2:.006AmpsX500=3Vdrop
R3.006AmpsX1000=6Vdrop3V + 3V + 6V = 12VPlacemeteracrosseachresisterandthesearethevoltagesyouwillobserve
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AC - ALTERNATING CURRENT
WHYDOICALLIT110VANDNOT115OR120?
Voltageisnotconstantbutsweepsfrom0Vto120V,thendownto0Vandandbackupto120V.
IntheUS,thistakesplace60timespersecond(hence,60HZ)orcyclespersecond.
Ifdrawnongraphwithtimehorizontal,plotformssinewaveandthatswhatonewouldseeonascope.
120V 12V AC DC 0V
0V
IfDCwasshowninthisway,therewouldbejusta12Vlineparallelto0V. Thevoltagecalledoutispeak,notaverage(orRMS).
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EXAMPLES OF AC LOADSAirconditioning:3KWrunning,startupsof5-6KW
Hotwaterheater:1500W=13amps@115VAC
Refrigeration:520W=4.35amps@115VAC
Toasters and hair dryers: 1500W= 13 amps
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ALTERNATING CURRENT CURCUITAlternatingCurrent(AC)isonewherethedirectionofcurrentisreversedatregularintervals.
The electrical generator feeding alternating current creates electric fields thatreverse their directions 120 times a second. This reversal alternates thecurrent backward and forward through the wires connecting to the powersource. The biggest advantage of AC is it allows the use of transformers bymeans of the alternating magnetic field.
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TRANSFORMERS
Demonstrationofinductancewithmagnet/coilandmeter.
Magnetandcoilandhowthisdeterminesfrequency.
Inductanceincontextofjumpinggapsintransformersandairtoskinorground.
Demonstrationofinductancethroughtransformer.
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Demonstrationofinductancethroughairwithsparkanduseweldingexampleforh.v.jumptostartwelding
Becausethevoltageishighandoscillating,itwilljumpgapsandiseasilytransmittedthroughcablesaswellasskin.
Becauseofinductance,voltagecanbemultipliedordividedwithtransformer.
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Number Of Coils For Step And Step Down Transformers
Thetransformersaboveareratedfor1.2KVAtoshowtheamperagechangewithdifferentvoltages.Theadvantageofthe240V5ampsisthatitwillallowsmallersizedwirestobeusedthanthe120V10amps.
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GROUNDSYSTEMONBOATSANDHOWACGROUNDANDDCNEGATIVEAREBONDEDANDTHEREFORECLAMPEDTO0V
Why is this is required for safety? Whythissometimesmakesaproperlybondedboatmorelikelytoactasgroundforlonglegsinmarina
Shorepowerisolatoroptions(transformerandsimple30+50amp
isolators)
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ACvoltagecanbesteppedupordowntomake220Vfrom110,or110from220.
Step up and Step down Transformers
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110canalsobetakenfromthe2legsof220V.
Worth mentioning:UnbalancedneutralHowshorepoweradaptorcordsmake110from240or240from110
Theyshouldhaveleadstoindicatepoweravailatpowerpostondock
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POWERVOLTS X AMPS = WATTS
Where: V=volts=differenceinpotentialAmps=current=chargedparticles=rateofflow
Watts=power=voltsxamps
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WHYPOWERREQUIREMENTSCANDETERMINEACAPPLIANCEVOLTAGES
Example 1:Alargepowerboathasabigairconditioningsystemthatrequires4.6KWforoneofthecompressors.Thats42ampsifthecompressorrunsat110.
Thatsprettybigwire,probablyaround#6ifitrunsthroughengineroom.
Ahugebreakertoo,notacommonone.Requiresaspecialholeshapeonpanel.
Ifthatcompressorranat220V,itwouldbe4600W=21amps,nobigdeal. 220V
#10or#12wireifinengineroomwith4-6conductors
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Other appliances with large current needs
Electricstoves-1.5to5kw(especiallyiftheyhaveanoven) Electricdryersupto9kw(onahomemodel) Somelargerefrigeratorsandfreezers SomelargeboatshaveACpoweredthrusters,windlassesorfurlers.
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WHY POWER REQUIREMENTS CAN DETERMINE BOATS ACSYSTEM VOLTAGESExample 2:
Aparticularsystemorappliancerequiresacertainamountofpower.ForInstance;anairconditioningsystemmayrequire4KWormuchmore,dictatingneedforanadditional120V,30ampor50ampinletjustforitself.
Itmayalsoneedtogoupto240v50ampsforitselfandtheotherairconditionerloads.
Example 3:CombinedloadsdemandmorepowerthanisavailablefromasingleStandardshorepowersupply.
Forinstance,itisdeterminedthataboatneeds10Kwofpower (voltsxamps).10,000Kw
115v =87amps
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Standard shore power offerings
120V,30amps03.6Kw-mostcommon 120V,50amps6Kw-fairlycommon
240V,50amps-12Kw-commoninlargemarinas
Common 30 Amp/125V Plug
50 Amp/ 125V Plug
50 Amp/ 125-250V Receptacle
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100 Amp 125/250V Plug and Inlet
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DC CIRCUIT DESIGN101Simple circuits and their components
Allcircuitsrequireatleasta:Battery(orDCsource)
Conductors
Load
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The Battery Storestheelectricalpowerbutcurrentwillnotstarttoflowuntilitstwoterminalsareconnectedtogetherviawireandaloaddevice(i.e.light,motor).
Thebatteryismadeofacoupleofdifferenttypesofmetalplatessurroundedbyanacid(electrolyte).
Ithasapositive(+)andanegative(-)terminal. Thewholesystemthroughouttheboathasa+andpart.
Aspowerisdrawnfrombattery,itschemicalsolutionchanges.Whenitisrecharged,thesolutionisreconstitutedanditregainsitsabilitytoproducepower
Thebatteryisratedinvoltsandinamphours.
Standardsystemvoltagesare12,24and32.
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Thebatterywillbeeithera12volt(byfarthemostcommon)oroccasionallya6volt(usuallyagolfcartbattery).
Ifboatisdesignedfor24or32voltsystem,thebatteriesarestackedin
seriesandthevoltsareadded.(Moreaboutthisinanotherlesson.)Conductors
Wireusedtocompletethecircuitandallowelectronflowfromonebattery
postthroughboat,throughloadandbackintobatterysotherpost.
Wireiscalledpositiveonthe(+)sideofthecircuitanditsanegative(-)onthefeedoftheload.
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Electronsflowfromnegativeposttopositivebutnotuntilthecircuitiscompleted.
Ifyouweretoconnectawireposttopostwithnoresistance,thefullamperageofthebatterywillbeallowedtoflowandsomethingbadwill
happen.
Thewireshouldbemultistrandsoitsflexibleandwontsnapfromfatigue
Itshouldbetinnedcoppertoresistcorrosion.
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Mostconnectionsaremadeusingcrimpterminations
Crimpsarecolorcodedtowiregauge.
Crimpsshouldbetinnedcopper.
Crimpswithstrainreliefandnyloncoveredarethebest.
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RECOMMENDED COLORS
ABYC says yellow for negative but black is still more common.
Different types of loads should have different color positive conductors, butthe positive colors will not be yellow or black.
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Some Typical Wire ColorsDC System:
Yellow=Negative(oftencalledgroundbutonlygroundedifitisconnectedtoearth)
Black=StillbeingusedasNegative.ABYCwantsthisreplacedwith yellow,butmostboatsaroundstillhavemostlyblack.
Red=Mostcommonpositivecolorofall.Mostduplexwillhavearedandblackorredandyellow
Blue=OnEuropeanboats,blueusuallynegative. Earth:
Boatsinterfacewiththewater=Earth=0Volts Usuallygreenorgreenwithyellowstripe. Negativesideofsystemusuallyconnectedwithwaterthroughtheearthor
groundterminal. Clampsitto0volts. ACsystemhasagroundportionandthatgroundbussisconnectedtoearthaswell.
Wiregauges
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AC System:In110Vsystems:oWhite=Neutral(agroundedconnector)-groundedashore.
oBlack=HotoGreen=Ground
In240systems:oRed=hotoBlack=hotoWhitenotusuallyusedasitisgroundedandthereforewouldbeassociatedwith110V
oGreenorGreenwwithYellowstripe=Ground.So,ifyouseeawirewithred-black-green,itsprobably240VAC. Ifwhite-black-green,probably110VAC.
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Wire GaugesGauge=wirediameter
Oftencalledoutasawgonwireorindocuments
oAwg=Americanwiregauge
Theheavierthegauge(lowernumber),themoreampsitwillcarryoHaslowerresistance,measuredinOhmsperfoot.
Thegaugesrunlikethisfromsmalltolarge:
26 24 2218 16 14 12 10 8 6 4 2 0(or1-0), 00 (2-0), 000(3-0), 0000 (4-0)
After4-0,theygotomcmsizes
Usuallyiflargerthan4-0required,wouldgotodoublelengthsof2-0or3-0
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AMPACITY OF WIRE & WIRE SIZE TABLES WiregaugesareusuallydeterminedusingABYCVoltage Drop Tables
oTable10orTable11
3%or10%drop.Sometypesloadshouldbe3%,somecanbe10%.(Moreabouttheselater.)
Lengthofrunequalsbothpositiveandnegative. ABYCalsohasatabletodetermineampacityofconductorsunder50V.
oIttakesintoaccountthetemperatureratingofinsulation.
Thereisanothertablethatcanbeaccessedonline(notassociatedwithABYC)thatallowsforslightlysmallergauges.(ABYCdoesnthaveaproblemwiththisguide.)
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http://www.midcoast.com/~aft/index2.html
http://www.midcoast.com/~aft/index2.htmlhttp://www.midcoast.com/~aft/index2.htmlhttp://www.midcoast.com/~aft/index2.html -
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Usethelargerwiresizeascalledoutbythetwotables.
Thistableisniceforlargercablesbuttheresistancefortherunshouldalsobecalculated.
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Eachgaugehasastandardcrosssection,measuredincm(circularmills).
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Thecmsareusedforcalculationofresistance,ifdoingwithformulainsteadofwiregaugetable.
Sizing wire for very heavy loadsInstallationmanualsformostdeviceswillgiveadequateimformationtosizewires
IfyouneedtofiguresomethingoutusethefollowingtabletofindCMsrequired,thengotoprevioustabletofindCMforwiregauges
Justpluginamps,lengthofrun,allowablevoltagedropandgetthecircularmilrequirementsforthecircuit
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HeresyourolebuddyGeoffsmethodfordeterminingwiresizeswhenover100amps:
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TYPES OF WIREDuplex
Twoconductors,insideajacket.
Usuallyapositiveandanegative(redandblackorredandyellow)
Mostcommonforaftermarketwiringoraddingpiecesofgear.
Usuallyonlyusedin20gaugeupto8gauge,sometimeslargerbutafterthesesizesitmakesmoresensetouseprimarybecauseits:
o
NotasstiffoDoesntalwaysgotosameplaceoMaywantdifferentcolorsoLargesizeshardtorunthroughboatoExpensivetostock
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PrimarySingleconductor.
Oftenusedbybuildersorinbigjobswheretwo-conductordoesntmakesense.
Availableinallsizes.
Triplex
3conductoroftenusedforshorepower.Colors:white,black,green.
Ilikeitflateasiertoworkwith(calledboatcable).
Alsousedforsomecombinationlightswhere2positivesand1negativerequired.
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Multi-conductorCouldbeanywherefrom3to100conductors.
Somemightbeinsizesaround18-12gaugeforlights,etc. Someintinygauges26-18forelectronicsystems.
CoaxSpecialcableforconductingRForaudioHasmulti-strandcenterconductorBradedoutershieldPVCouterjacketRatedforimpedance
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LOADSCommon Types of DC LoadsLights
NothingspecialhereRatedinwattsParallelcircuitOftenafewactivatedbyoneswitchWiregaugeandfusefortotalamps.Usuallybluepositivewire(grayfornavigationlights)
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Motors and PumpsWiregaugeandfuseforlockedrotor.
Manufacturersusuallycalloutrunningamps.
Usuallybrownpositive. Start Circuits
Theonlycircuitsthatdontneedovercurrentprotection.
Batterycableupto4-0ormore---runsmeasuredininches.
Usuallyredwire. Useabatteryswitch.
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Windlasses & ThrustersVeryheavyloads.
Commonly100to350amps-keeprunsshort!
Useabatteryswitch,andTNLorANLfuse,orlargebreaker.
Electronics
Relatively low current needs.
Clean Power desirable
Always fuse to protect wire.
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Other required parts to a circuitOvercurrent Protection
Requiredinallcircuits(otherthanstartermotor)todisconnectpowerbeforeampscandamageawireordevice.
Canbeafuseorbreaker.
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SwitchRequiredinallcircuitstoactivate/deactivate.
Functionoftenpartofcircuitbreaker.
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POWERVOLTS AMPS WATTS
Where: V = Volts = difference in potentialAmps = current = charged particles = rate of flowWatts = power = Volts x Amps
The difference between 12V and 24 V when calculating power
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WHY POWER REQUIREMENTS CAN DETERMINEDC SYSTEM VOLTAGES
Example 2:ASidepower9HPThrusterrunat12voltsrequires680amps
At12V,assumearunof64frommanufacturerstableofwiregauge/run-2lengthsof4-0forboth+andruns
At24V,samerunof64mfrstableofwiregauge/runrequires:1lengthof3-0Cable
http://www.imtra.com/downloadTypes/Side-Power_DC_Thrusters_Spec_info.pdf
AtthispointIwouldbethinkingaboutmountingbatteriesforwardbutthereareotherconsiderations
Theseexamplesaresimilartotherequirementsofwindlasss,electricwinchesandotherpowerfulpiecesofgear.
http://www.imtra.com/downloadTypes/Side-Power_DC_Thrusters_Spec_info.pdfhttp://www.imtra.com/downloadTypes/Side-Power_DC_Thrusters_Spec_info.pdf -
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WHY POWER REQUIREMENTS CANDETERMINE DC SYSTEM VOLTAGES
Example 3:AnITTJABSCOwaterpressuresystempump.
At12V,pumpdraws24amps.Assumearunof50andanallowablevoltagedropof10%.(Iwouldrecommend3%onthistypeofsystemtoavoidcustomercomplaints)oFromABYCconductorsizingtable:#8wirerequiredfor10%---#4requiredfor3%
At24V,pumpdraws12amps.Samerunof50.
oFromABYCconductorsizingtable:#12wirerequiredfor10%;#6requiredfor3%
#8wirecoststhecustomer$55andweighsperhaps12lbs? #12wirecoststhecustomer$19andweighsperhaps4lbs
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Basic AC Circuit Design
Allcircuitsrequireatleast: Source
Conductors
Load
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SOURCE
MostoftenACissuppliedthroughshorepowerpostatmarina
Canalsobegeneratedaboardthroughgenset(usuallybeconfiguredfor120or240V
InvertersbecomingmorecommonoCanbeorderedin120or240VACoutputs, 12or24VDCinputs
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Typical Power
MostcommonVoltagesare: 110(120)--30ampand50amp
220(240)50ampand100amp IntheUS,ACisat60Hz110Visthemostcommon. InEurope,ACat50Hz240Visthemostcommon.
Cannotrunstuffonthewrongcyclesorwrongvoltage.oBadthingscanhappenifyoudothis.
Motorsrunatwrongspeedwhenusedwithwrongfrequency.
V l b d d i h f di d li
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Voltagescanbesteppedupordownwithtransformersasdiscussedearlier.
Power is brought into boatthroughinlet.
Inlet, Power cord, breaker and Docks Receptacle all rated same
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110V System includes 3 conductors
Black=Hot=Ungroundedconductor=110Vpotentialfromground.
White=Neutral=Returnpathtocompletecircuit.
Groundedconductorashoreonlyoratsourceofgeneration. Shouldmeasure0Vfromground Reversepolarityindicatoroperatesoffthisvoltage
Green=Ground=EarthoMustbeconnectedtoshipsearthingsystem
240V System includes:Black=Hot=Ungroundedconductor=120Vpotentialfromground.
Red=Hot=Ungroundedconductor=120Vpotentialfromground.
Otherside
Green=Ground=Earth
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White=Neutral=Groundedconductor0Vpotentialfromground. Whiteisbroughtintoboatandisusedforneutralbusstoprovide110V.
Potentialtoredandblacklegs.
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Voltages present in 240 VAC System
120V RED - MeasuredwithVOM0V GREEN and WHITE
120V BLACK
RedtoBlack=240VAC. RedtoWhiteorground=120VAC. BlacktoWhiteorground=120VAC.
Canusethispowersourcefor240VACortwolegsof120VAC.
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CONDUCTORSWire Shouldbemarinewiretinnedcopper,flexiblemultistrand. MustbeULlisted.
SamerequirementsaswireusedinDCSystemsexcept600Vinsulationrating.
Ifwireisflat,itissometimescalledboatcable. ACwiresinloomifrunwithDC.
Protectfromchafe.
Mustconformtocolorcodes.
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AC System:In110Vsystems:oWhite=Neutral(agroundedconnector,groundedashore).o
Black=Hot.oGreen=Ground.
In240Vsystems:oRed=Hot.oBlack=HotoWhitenottypicallyusedasitisgroundedandthereforewouldbeassociatedwith110V.
oGreenorGreenw/Yellowstripe=Ground.If you see a wire with red-black-green, its probably 240 VAC.If white-black-green, probably 110 VAC.
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Gauges Calculatetotalwattageofcircuitandusetablestodeterminegauge.
Motor-wireandprotectforlockedrotor.
oManufacturerofmotorwillgivestartupcurrent,operatingcurrentandlockedrotor.
Differentsizerequiredwhenrunthroughengineroom.
Whenaddingacircuit,considereffectonoverallsystemcapacityanditsampacity.
Wewilldoloadcalculationsforentiresystemsinalaterlesson.
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E-11 - Table VII
Thistableconsistsoffivechartsfordifferentsizebundles.
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Common Types of AC LoadsBattery ChargersNotahugeload-approximately1/10ththeampsofthechargersoutput.
LightsNothingspecialhere.Ratedinwatts. Parallelcircuit-oftenafewactivatedbyoneswitch.Wiregaugeandfusefortotalamps.
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Motors and PumpsInductiveload.
Wiregaugeandfuseforlockedrotor. Manufacturersusuallycalloutsurge,lockedrotor,andrunningamps.
Air Conditioning Veryheavysurgesandheavyoperationwattage. OftendeterminestheACpowerrequirementsforboat.
Usuallymultiplebreakers. Sometimeshasitsownshorepowerinlet.
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Water heater Purelyresistiveload,constantwhenthermostathasitrunning.
Frequently1500W(about13amps). Electronics
Relativelylowcurrentneeds.
Cleanpowerdesirable.
Alwaysfusetoprotectwire.
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Other required parts to a circuitOvercurrent Protection
Requiredinallcircuits(otherthanstartermotor)todisconnectpowerbeforeampscandamageawire ordevice.
Canbeafuseorbreaker.
Usuallyfusemountedinadevicebymanufacturerandwiringthroughboatprotectedbyabreaker.
Thebreakeralsoactsasaswitch.
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Earth
Boatsinterfacewiththewater=Earth=0V.
Usuallygreenorgreenwithyellowstripe.
Negativesideofsystemusuallyconnectedwithwaterthroughtheearthorgroundterminal.
Clampsitto0V.
ACsystemhasagroundportionandthatgroundbussisalsoconnectedtoearth.Allmetalcasesinsystemgrounded.
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