GarrettCom 4K16 User Manual
Page 37
Magnum 4K16 Switches Installation and User Guide
(12/05)
31
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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 4K-Series -48VDC, 24VDC & 125VDC
Dual-Source Option units are identical to the standard AC-powered models. Refer to the
main sections of this Installation and User Guide for a detailed description of the
Magnum 4K-Series Switches.
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, 24VDC and 125VDC power terminal block
on the Magnum 4K-Series Switch (shown in Figure )
The -48VDC terminal block on the Magnum 4K-Series Switch is located on
the right rear of the unit and is equipped
with five (5) screw-down lead posts (see
Fig 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.
FigureC5.0: -48VDC Dual-Source, wiring connections to the External
Terminal Block on a Magnum 48VDC with Dual-Source option
Note: The GND should be hooked up first. The 4K unit has a floating ground, so the
user may elect to Ground either + or = terminal to suit the customer’s use.
GND
FUSE
+
-
SUPPLY
A+
A-
B-
B+
GND
CHASSIS
HUB
36-70VDC
GND
A+ A- B- B+
36-70VDC