Rev09-10 Electrical Fundimentals-sequence 1

8/8/2019 Rev09-10 Electrical Fundimentals-sequence 1

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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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Rev09-10 Electrical Fundimentals-sequence 1

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