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Magnum 4K220 Switches Installation and User Guide
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 Switch 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 Switch 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 Switch 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 Switch 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 Switch is operating from the other source.
e)
The Switch 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 power terminal block on the Magnum 4K-
Series Switch (shown in Figure )
The -48VDC terminal block on the Magnum 4K-Series Switch, as shown in Fig C5.0 is
located on the right rear of the unit and
is equipped with five (5) screw-down
lead posts. The primary terminals are
identified as positive (A+), negative
(A-), and the secondary power
terminals as negative (B-),
positive(B+), and the chassis "earth"
or ground (GND), #6 nut.
Figure C5.0: -48VDC Dual-Source, wiring connections to the External
Terminal Block on a Magnum 48VDC with Dual-Source option
Note: Before connecting to Terminal Block of –48VDC, 24VDC or 125VDC, always
use a digital voltmeter to measure the output voltage of the power supply and
determine the lead which is more "+ve potential Lead". The more "+ve" voltage
terminal lead from 48V or –48V Power supply must be connected to the post labeled
"+".
The GND can be hooked at the last.
www GarrettCom com
.
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A+
A-
B-
B+
GND
A+ A- B- B+
36-70VDC
25
(10/04)
HUB
SUPPLY
+
FUSE
-
CHASSIS
GND
36-70VDC
GND
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