© 2010 Magnum Energy, Inc.
DC Wiring
This section describes the MMS Series inverter’s required DC wire sizes
and the recommended disconnect/overcurrent protection, and how to
make the DC connections to the inverter and the battery bank.
DC Wire Sizing and Overcurrent Protection
It is important to use the correct DC wire to achieve maximum ef-
fi
ciency from the system and reduce
fi
re hazards associated with
overheating. See Table 1 to select the minimum DC wire size needed
based on your inverter model. If the distance from the inverter to the
battery bank is greater than 3 feet, use Table 2 to help determine
the minimum recommended cable sizes for longer distances. Always
keep your wire runs as short as practical to help prevent low voltage
shutdowns, and keep the DC breaker from nuisance tripping (or open
fuses) because of increased current draw. Undersized cables can also
lower the inverter’s peak output voltage, as well as reduce its ability
to surge heavy loads.
Info:
The DC wires must be color coded with colored
tape or heat shrink tubing; RED for positive (+), BLACK
for negative (-), and GREEN for DC ground.
14
2.0 Installation
The DC wires must have soldered and crimped lugs, crimped copper
compression lugs, or aluminum mechanical lugs. Soldered connec-
tions alone are not acceptable for this application.
Do not attempt to use a vehicle metal frame in place of the nega-
tive connection or DC ground. The inverter requires a reliable
negative and ground return path directly to the battery.
DC wires and cables should be tied together with wire ties or
electrical tape approximately every 6 inches. This helps improve
the surge capability and reduces the effects of inductance,
which improves the inverter waveform and reduces wear on the
inverter’s
fi
lter capacitors.
Use only copper wires with a minimum temperature rating of
75°C.
To ensure the maximum performance from the inverter, all con-
nections from the battery bank to the inverter should be mini-
mized; the exceptions are the DC overcurrent disconnect in the
positive line.
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