Samlexpower PST-300-12 Owner's Manual - Section 8 |
30 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 31
seCtIOn 8 |
Installation
uptoAWG#1.WiresthickerthanAWG#1aredesignatedAWG1/0,AWG2/0,AWG3/0
andsoon.Inthiscase,increasingAWG#denotesthickerwire.
TheDCinputcircuitisrequiredtohandleverylargeDCcurrentsandhence,thesizeof
the wires and connectors should be selected to ensure minimum voltage drop between
the battery and the inverter. Thinner wires and loose connections will result in poor
inverterperformanceandwillproduceabnormalheatingleadingtoriskofinsulation
meltdownandfire.Normally,thethicknessofthewireshouldbesuchthatthevoltage
drop due to the current & the resistance of the length of the wire should be less than
2%.Useoilresistant,multi-strandedcopperwirewiresratedat90ºCminimum.Donot
use aluminum wire as it has higher resistance per unit length. Wires can be bought at a
marine/weldingsupplystore.
effects of low voltage on common electrical loads are given below:
- Lighting circuits - incandescent and Quartz Halogen:A5%voltagedropcausesan
approximate10%lossinlightoutput.Thisisbecausethebulbnotonlyreceivesless
power,butthecoolerfilamentdropsfromwhite-hottowardsred-hot,emittingmuch
less visible light.
- Lighting circuits - Fluorescent:Voltagedropcausesanearlyproportionaldropin
light output.
- Ac induction motors: Thesearecommonlyfoundinpowertools,appliances,well
pumpsetc.Theyexhibitveryhighsurgedemandswhenstarting.Significantvoltage
drop in these circuits may cause failure to start and possible motor damage.
- PV battery charging circuits: These are critical because voltage drop can cause a dis-
proportionatelossofchargecurrenttochargeabattery.Avoltagedropgreaterthan
5%canreducechargecurrenttothebatterybyamuchgreaterpercentage.
Fuse Protection in Battery circuits
Abatteryisanunlimitedsourceofcurrent.Undershortcircuitconditions,abatterycan
supplythousandsofAmperesofcurrent.Ifthereisashortcircuitalongthelengthof
thecablesthatconnectsthebatterytotheinverter,thousandsofAmperesofcurrent
can flow from the battery to the point of shorting and that section of the wire will be-
comered-hot,theinsulationwillmeltandthecablewillultimatelybreak.Thisinterrup-
tionofveryhighcurrentwillgenerateahazardous,hightemperature,high-energyarc
withaccompanyinghigh-pressurewavethatmaycausefire,damagenearbyobjectsand
cause injury. To prevent occurrence of hazardous conditions under short circuit condi-
tions,anappropriatefuseshouldbeusedinthebatterycircuitthatwilllimitthecurrent,
blowinaveryshorttimeandquenchthearcinasafemanner.forthispurpose,ULClass
TfuseorequivalentwithAmpereInterruptingCapacity(AIC)ofatleast10,000Ashould
beused(AsperULStandard248-15).Thisspecialpurposecurrentlimiting,veryfastact-
ingfusewillblowinlessthan8msundershortcircuitconditions.Appropriatecapacity
oftheaboveClassTfuseshouldbeinstalledwithin7”ofthebatteryPlus(+)Terminal.
The fuse will require a corresponding fuse holder.