Samlexpower PST-15S-12E Owner's manual - Section 8 |
32 | SAMLEX AMERICA INC.
- Lighting circuits - fluorescent: Voltage drop causes a nearly proportional drop in
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% can reduce charge current to the battery by a much greater percentage.
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,anappropriatefuseshouldbeusedinthebatterycircuitthatwilllimitthecur-
rent,blowinaveryshorttimeandquenchthearcinasafemanner.forthispurpose,UL
ClassTfuseorequivalentwithAmpereInterruptingCapacity(AIC)ofatleast10,000A
shouldbeused(AsperULStandard248-15).Thisspecialpurposecurrentlimiting,very
fastactingfusewillblowinlessthan8msundershortcircuitconditions.Appropriate
capacityoftheaboveClassTfuseshouldbeinstalledwithin7”ofthebatteryPlus(+)
Terminal. The fuse will require a corresponding fuse holder.
WARninG!
Useofanappropriatelysizedexternalfuseasdescribedaboveismandatoryto
provide safety against fire hazard due to accidental short circuit in the battery
wires.PleasenotethattheDCsidefuse(s)insidetheunitaredesignedtopro-
videprotectiontotheinternalcomponentsoftheinverter.ThesefuseswillNoT
blow if there is a short circuit along the length of wires connecting the battery
and the inverter.
Recommended Sizes of Wires and external Fuses
Thefollowingsizesofwiresandexternalfusesarerecommended.Thedistanceof3ft./
6ft./10ft.isthedistancebetweenthebatteryandtheinverter.Therunninglengthof
routing of the wire should be considered if the wiring run is not straight but circuitous.
The recommended size of wires will limit the voltage drop to 2% of the nominal battery
voltage(0.24Vfor12Vbatteryand0.48Vforthe24Vbattery)
Thelengthofthewireforcalculatingvoltagedrophasbeentakenas2timesthe
distance between the inverter and the battery assuming that 2 lengths of wires (one