Samlexpower SAM-1500C-12 Owner's manual - Making Dc Side Connections
12 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 13
important Wiring/cabling information
Although wires and cables are good conductors of electric current, they do have some
resistance, which is directly proportional to the length and inversely proportional to the
thickness(diameter)i.e.resistanceincreasesinthinnerandlongerwires.Currentflowing
through resistance produces heat. Cables and wires are covered with insulating material
thatcanwithstandaspecifiedtemperatureoftheconductorunderspecifiedconditions.
Toensurethattheinsulationisnotdamagedduetoexcessiveoverheating,eachwiresize
hasamaximumallowablecurrentcarryingcapacitycalled"Ampacity"whichisspecified
byNECTable31.15(B)(17).Further,NECalsospecifiesthatwiresizeshouldbebasedon
Ampacity-1.25timestheratedcurrentflow.
resistance of wires and cables produces another undesirable effect of voltage drop. Volt-
agedropisdirectlyproportionaltotheresistanceandthevalueofcurrentflow.Voltage
dropproduceslossofpowerintheformofheat.Inaddition,excessivevoltagedropfrom
the battery to the inverter may prematurely shut down the inverter due to activation of
the Low Input Voltage Protection Circuitry of the inverter (10.5 ± 0.5V). DC cables should
besizedtoensuremaximumvoltagedropislimitedtolessthan5%.
effects of low voltage on common electrical loads are given below:
Lighting circuits – incandescent and Quartz/Halogen: Loss in light output because the
bulbnotonlyreceiveslesspower,butthecoolerfilamentdropsfromwhite-hottowards
red-hot, emitting much less visible light.
Lighting circuits – fluorescent: Voltage drop causes an early proportional drop in
light output.
ac induction motors: These are commonly found in power tools, appliances, etc. They
exhibitveryhighsurgedemandswhenstarting.Significantvoltagedropinthesecircuits
may cause failure to start and possible motor damage.
requirement of fuse in Battery connection
A battery is a very large source of current. If there is a short circuit along the length of
the cables that connect the battery to the inverter, thousands of Amperes of current can
flowfromthebatterytothepointofshortingandthatsectionofthecablewilloverheat,
theinsulationwillmeltandislikelytocausefire.Topreventoccurrenceofhazardous
conditionsundershortcircuit,fusewithAmpererating≥themaximumcontinuouscur-
rent drawn by the inverter but ≤ the Ampacity of the connecting cable should be used
in the battery connection. The fuse should be fast acting Class-T or Marine rated battery
fuse Type Mrbf. rating of fuse is shown in Table 4.1 below. The fuse should be installed
as close to the battery Positive terminal as possible, preferably within 7”. Please note that
thisfuseisrequiredtoprotectthecablerunfromthebatterytotheinverteragainstshort
circuit. The inverter has its own internal DC side fuse(s) for internal DC side protection.
making Dc Side connections
RecommendedcableandfusesizesforconnectingbatteryaregiveninTable4.1.
Themaximumcurrentforcablesizing/fuseratinghasbeenconsideredat1.25times
rated continuous current draw at the rated output power.