10 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 11
SeCtIOn 5 |
Installation
Load connection: The load is connected to the terminals marked “Load +” (4) and
“Load - ” (3) through 32V, 25A fuse (f2) (See details below under heading “External
fuses”). Please ensure that the polarity of the connection is correct - Positive of the load
to the “Load +” terminal (4) and the Negative of the load to the “Load - ” terminal (3).
Battery connection: The Positive of the battery is connected to the “B” terminal
(6) and the Negative of the battery to the “Battery - ” terminal (5) through 32V, 25A fuse
(f1) (See details on page 5 under heading “External fuses on Battery and Load Sides”).
Recommended Battery capacity: Battery should not be charged at very high current.
Normally, as a rule of Thumb, the maximum charging current should be limited to 10%
of the Ah capacity at 20 Hour rate unless higher current is allowed by the manufacturer.
Higher charging current produces higher heating which reduces the life of the battery.
further, higher charging current will not re-charge the battery to full 100% capacity
unless the charging voltage is increased proportionately. It is recommended that the
capacity of the battery used with this unit should be in the range of 40 to 100Ah.
Dc oUtPUt WiRe SiZinG
Use AWG #10, 90°C / 194°f insulation wire for the load and battery connections for a
distance of up to 3 ft. Thicker wire will be required for distance longer than 3 ft. (See
Table 5.1 below). USe tHicKeR WiRe oUt tHe 2 SiZeS cALcULAteD BASeD on tHe FoL-
LoWinG 2 conSiDeRAtionS:
1. Safety of conductor insulation
Current (I) flowing through resistance (r) of conductor produces power loss (I
2
r) in
the form of heat which results in temperature rise in the conductor. Temperature rise
is higher for higher current, higher resistance (longer length and thinner cross section
produce higher resistance) and higher ambient temperature. Temperature rise higher
than the temperature rating of conductor insulation will melt / burn the insula-
tion resulting in possibility of electrical shock and fire. The National Electrical Code
specifies maximum current flow (ampacity) through a particular wire size (normally
specified as cross-section in American Wire Gauge (AWG) for a particular tempera-
ture rating of conductor insulation, ambient temperature and type of surrounding
medium (like free air, raceway, etc.). NEC further specifies that the ampacity of the
wire should be 1.25 times the maximum current flow. The maximum output current
in the unit is 25A.
-
The maximum output current in the unit is 25A. Hence, the ampacity of the wires as per
NEC should 1.25 x 25 = 31.25A or say 40A
-
As per NEC Table 310.15(B)(17) for 90°C / 194°f conductor insulation, free air, 40°C / 104°f
ambient and ampacity of 40A, the minimum conductor size should be AWG #10.
2. Limiting Voltage Drop along the Length of the Wiring
Current flowing through resistance produces voltage drop. Voltage drop is higher
for higher resistance (longer length and thinner cross section produce higher
