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The DC input circuit is required to handle very large DC currents and hence, the size
of the cables and connectors should be selected to ensure minimum voltage drop
between the battery and the inverter. Thinner cables and loose connections will result
in poor inverter performance and will produce abnormal heating leading to risk of
insulation melt down and fire.
Use oil resistant, multi-stranded copper wire cables rated at 90 º C minimum. Do not
use aluminium cable as it has higher resistance per unit length. Cables can be bought
at a marine / welding supply store
A battery is an unlimited source of current. Under short circuit conditions, a battery
can supply thousands of Amperes of current that will melt the cables and pose a
safety and fire hazard. To prevent damage due to short circuit in the battery cables,
an appropriate fuse should be used that has the required current interrupting capacity
(termed AIC - Ampere Interrupting Capacity). For this purpose, fuse with AIC rating of
10000 A at 14 V / 5000 A at 32 V or higher should be used. Class T fuses or MRBF Series
of fuses (made by Cooper Bussmann) may be used. The fuse should be installed in
line with the Positive terminal of the battery & should be located within 7" from the
battery terminal.
The following size of cables and fuse are recommended. The distance shown is
the distance between the battery and the inverter. The recommended size of the
cables will limit the voltage drop to approximately 2% (The length of the cable for
calculating the voltage drop has been taken as 2 times the distance between the
inverter and the battery assuming that two (one positive and one negative) cables are
used for the connection).
Distance up to 3’
Distance up to 6’
Ampere rating of fuse
PST-30S-12A
# 12 AWG
# 8 AWG
40 A
PST-30S-24A
# 14 AWG
# 10 AWG
20 A
CAUTION!
The input section of the inverter has large value capacitors connected
across the input terminals. As soon as the DC input connection loop
[Battery (+)
a
fuse
a
inverter (+)
a
inverter (-)
a
battery (-)] is
completed, these capacitors will start charging and will momentarily
draw very heavy current that will produce sparking on the last contact
in the input loop even when the on / off switch on the inverter is
in the off position. Ensure that the fuse is inserted only after all the
connections in the loop have been completed so that the sparking is
limited to the fuse area.
Using proper DC cable termination
The battery end and the inverter end of the cables should have proper terminals that
will ensure a firm and tight connection.
DC input terminals
The DC input terminals have a tubular hole with a set screw. A suitable pin type
of copper terminal should, therefore, be used on the cable end.
Do not insert the
stranded bare end of the cable directly into the tubular hole as the set screw will not
pinch all the strands and will thus make only a partial and loose contact.
For thicker
cables, a suitable adapter with pin type of termination should be used.
There should
be no stray wire strands protruding from the terminals as these may produce a short
circuit due to the close vicinity of the plus and minus terminals.
Battery cable set provided
For convenience, a 3' battery cable set with battery clips and a 3' battery cable set with
cigar plug have been provided. These can be used if it is possible to install the inverter
close to the battery.
