Preventing reverse polarity on the input side
When making battery connection on the input side, make sure that the polarity of battery
connection is correct (Connect the positive of the battery to the positive terminal of the
inverter and the negative of the battery to the negative terminal of the inverter). If the input
is connected in reverse polarity, DC fuse(s) inside the inverter will blow and may also cause
permanent damage to the inverter
Connection from the batteries to the DC input side of the inverter – cable and fuse
sizes
The flow of electric current in a conductor is opposed by the resistance of the conductor.
The resistance of the conductor is directly proportional to the length of the conductor and
inversely proportional to its cross-section (thickness). The resistance in the conductor
produces undesirable effects of voltage drop and heating.
Thus, thicker and shorter
conductors are desirable
. The size (thickness / cross-section) of the conductors is desig-
nated by AWG (American Wire Gauge).
Please note that a smaller AWG # denotes a thicker
size of the conductor.
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
The cables from the battery to the inverter should be protected by a suitable, very fast
acting DC fuse. Use a DC fuse of the appropriate capacity in line with the positive cable.
The fuse should be within 18” from the battery.
Type ANN fuses with Fuse Block 4164 made
by Bussmann are recommended.
The following size of cables and fuses 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 4’
Distance up to 6’
Ampere rating of fuse
PSE-24125A
# 4 AWG
# 2 AWG
125 A
PSE-24175A
# 2 AWG
# 1/0 AWG
175 A
PSE-24275A
# 1/0 AWG
# 2/0 AWG
275 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 ( B
Y
Y
Y
Y
Y
fuse
Y
Y
Y
Y
Y
in
Y
Y
Y
Y
Y
inverter -
Y
Y
Y
Y
Y
battery negative) 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.
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