Xantrex XPower Inverter 3000 Installation Manual page 19

DC Disconnects and Over-Current Devices
The DC circuit from the battery to the XPower inverter must be
equipped with a disconnect and over-current device. This usually
consists of a circuit breaker, a "fused-disconnect," or a separate
fuse and DC disconnect. Do not confuse AC circuit breakers or
fuses with DC-rated ones. They are not interchangeable. The
rating of the fuse or breaker must be matched to the size of cables
used in accordance with the applicable installation codes. The
breaker or disconnect switch and fuse should be located as close
as possible to the battery, in the positive cable. Applicable codes
may limit how far the protection can be from the battery.
To select the correct fuse type and size:
1. Determine the total short-circuit current rating for each
battery, based on the battery manufacturer's published
short-circuit current sourcing ratings for the battery. Then
determine the total for your battery bank.
For example:
If you are using one battery to power your inverter and
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its short-circuit current rating is 500 A, the total short-
circuit current rating is 500 A.
If you are powering your XPower inverter with two 12 V
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batteries connected in parallel, and each battery has a
short-circuit current rating of 500 A, the total short-
circuit current rating is 1000 A.
If you are powering your XPower inverter with two 6 V
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batteries connected in series, and each battery has a
975-0556-01-01
Choosing an Appropriate Location and Mounting Orientation
short-circuit current rating of 500 A, the total short-
circuit current rating is 500 A.
IMPORTANT: For batteries connected in parallel, the total
short-circuit current rating is the sum of the short-circuit
current ratings of all of the batteries connected in parallel. For
batteries connected in series, the total short-circuit current
rating is equal to the short-circuit rating of the battery with the
highest short-circuit rating. It is not the sum of all the short-
circuit current ratings taken from each connected battery.
2. Once you have determined the total short-circuit current
rating of your batteries, select a fuse or circuit breaker that
has:
a short-circuit interrupting capacity at least equal to the
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total short-circuit current rating of your battery bank,
and
a DC voltage rating of at least 16Vdc, and
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a current rating no more than the values given above.
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3. If a fuse is used rather than a circuit breaker, a disconnect
switch located between the battery and the fuse is
recommended, to allow the circuit to be de-energized when
replacing the fuse.
Fuses and circuit breakers can be bought at any RV supply
store or electrical products store.
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