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MX28B-400 +24V Product Manual
990-9218 17
5.3 Battery Connections
5.3.1 Battery Disconnect
An external circuit breaker (not supplied) is required in the negative line (located at the battery
end) to protect the cables from the battery to the MX28B dc power plant. The power plant can
monitor auxiliary contacts from this breaker.
5.3.2 Cable Sizing Considerations
The battery cable(s) should be sized sufficiently large to limit the voltage drop from the MX28B
dc power plant to the battery during charging per system design requirements. The cable(s)
must also carry the full load current during battery operation. If assistance is required to
determine the necessary cables for the application, contact your sales representative or APC DC
Network Solutions Inc..
5.3.3 Connecting the Cables
The battery cable connections are located at the top rear of the unit as shown in Figure 4.6-1.
The battery positive (+24V bus) and battery negative (Return bus) buses each provide two sets
of threaded 3/8”-16 holes on one-inch centers for connecting two-hole battery cable lugs.
Connect the battery cables as applicable using 3/8”-16 bolts (not provided) and tighten them
with a torque wrench to 200 in-lbs.
***** CAUTION *****
Make certain that the battery polarity is correct when making connections to the Model
MX28B dc power plant. Incorrect connection could cause severe equipment damage.
5.4 DC SYSTEM GROUNDING
THE NEGATIVE BATTERY CONNECTION (RETURN BUS) FOR THE POWER
PLANT MUST BE CONNECTED TO THE MASTER STATION GROUND. THE LEFT
END OF THE RETURN BUS PROVIDES A PAIR OF THREADED 3/8”-16 HOLES ON
1-INCH CENTERS FOR CONNECTION OF A TWO-HOLE LUGGED CABLE TO THE
MASTER STATION GROUND. DETAILS FOR THIS CONNECTION SHOULD BE
PROVIDED IN THE SITE ELECTRICAL GROUNDING PLAN.
5.5 Rectifier Installation
The APC DC Network Solutions Inc. Model MRF28H27BV rectifiers are shipped in separate
containers. Follow the procedure below to install a rectifier.
1) Remove the rectifier from its shipping container.
2) Remove the rectifier retaining screw from the shelf position where the rectifier is to be
installed.
3) Slide the rectifier into the shelf between the guides until it is fully seated.
4) Fasten the rectifier in place with the rectifier retaining screw.
Since all adjustments are made from the system control unit, no rectifier adjustments are
necessary.