GarrettCom Magnum 3000 - Manual (Page 57)

Magnum 3000 Stackable Hubs Installation and User Guide (07/06)
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GND: Terminal for “earth” or ground wire connection to the hub chassis
Input: Two separate sources, each at 120 - 160 VDC
Power Consumption: Model 3024 NEBS: 18 watt typical, 30 watts max.
Power Consumption: Model 3012 NEBS: 10 watt typical, 20 watts max..
With the exception of the dual DC input power connections and the power supply, all
specifications and configuration options for the Magnum 3000s -48VDC with this Dual-
Source option are identical to those listed in the Magnum 3000’s Installation and User
Guide, including Appendix B “Internal DC Power Supply Option”
C2.0 Magnum 3000 hubs with -48VDC, 24VDC & 125VDC Dual-Source option
The 3000s Hub 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 3000s unit with the -48VDC, 24VDC &
125VDC Dual-Source Option is identical to the standard AC-powered model. Refer to
the main sections of this Installation and User Guide for a detailed description of the
Magnum 3000s units and Configuration options.
C3.0 DUAL-SOURCE OPTION, THEORY OF OPERATION
The Dual-Source DC power option is designed using diodes inside of the
chassis 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 unit. This allows
the unit 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 3000s unit 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 3000s unit 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 3000s 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 3000s 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 3000s is operating from the other source.
e) The 3000s will not receive power (and will not work) when both inputs are simultaneously
absent or are both incorrectly connected.
GND
FUSE
+
-
SUPPLY
A+
A-
B-
B+
GND CHASSIS
HUB