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Magnum 8000X Mixed-Media Fiber Hubs Installation and User Guide (05/ 02)
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The hub models with the internal -48VDC, 24VDC &125VDC Dual-Source
power supply are designed for installations where a battery plant is the power source,
and where two separate power sources are utilized in order to increase operational
uptime and to simplify maintenance.
The functionality of the Magnum 8000X-48VDC, 24VDC or 125VDC Dual-
Source Option hubs are identical to the standard AC-powered models. All Port
Module, SNMP and stacking options are available for configuration with Dual-Source
Option units. Refer to the main sections of this Installation and User Guide for a
detailed description of the Magnum 8000X Hubs.
C3.0 DUAL-SOURCE OPTION, THEORY OF OPERATION
The Dual-Source DC power option is designed using diodes inside of the hub
on each DC power input line. A diode is
placed in each of the four input lines
(behind the four external power connection
terminals) so that power from an external
source can only flow into the hub. This
allows the hub to operate whenever DC
power is correctly applied to either or both
of the two inputs.
C4.0 FEATURES AND BENEFITS OF THE DUAL-SOURCE DESIGN
a) The hub can receive power from either input, “A” or “B”. The hub will normally draw its
power from the DC source with the highest voltage at a given time.
b) The hub will not allow power to flow from a higher voltage input to a lower voltage input, i.e.
the two DC power sources are not mixed together by the hub.
c) When one correct DC input is present, the hub will receive power if the other DC input is
absent, or even if it is connected with reverse polarity or shorted or grounded.
d) Reverse polarity connections, if they should accidentally occur on either input, will not
damage the hub or power supply internally (nor will it blow the fuse in the internal power
supply) because of the blocking action of the diodes. This is true even if one input connection
is reversed while the hub is operating from the other source.
e) The hub will not receive power (and will not work) when both inputs are simultaneously
absent or are both incorrectly connected.
C5.0 INSTALLATION
This section describes the proper connection of the -48VDC, 24VDC &
125VDC dual source leads to the -48VDC, 24VDC & 125VDC power terminal block
on the Magnum 8000X hub (shown in Figure C4.0).
The -48VDC terminal block on the Magnum 8000X is located on the right
rear of the unit and is equipped with five (5) screw-down lead posts (see Figure C5.0).
The primary terminals are identified as positive (A+), negative (A-), and the secondary
power terminals as negative (B-), positive (B+). The chassis “earth” or ground (GND),
is a threaded post with a #6 nut. The dual source terminal block for 24VDC and
125VDC are similar.
GND
FUSE
+
-
SUPPLY
A+
A-
B-
B+
GND
CHASSIS
HUB