Cisco 3800 Series Quick Start Manual page 23

Figure 18 Connecting Source A and Source B with Common Positive Terminals
Va voltage = Vb voltage (within 0.25 V)
Va
+
+
Vb
In Figure 19, source A and source B are wired with opposite polarity grounds. Do not use this configuration.
Do not use the DC input configuration shown in Figure 19.
Caution
Figure 19 Source A and Source B Wired with Opposite-Polarity Grounds
Va Va
+ +
+ +
Vb Vb
Connecting the Router to Backup Power
The Cisco 3845 router operates in redundant mode when two power supplies are installed. The Cisco 3825 router has one
internal power supply and a connector for mating to an external backup power source.
To connect the Cisco 3825 router to the external Cisco Redundant Power System (RPS), remove the RPS connector cover from
the bezel and connect the RPS cable. (See Figure 20 and Figure 21.)
See the Cisco RPS-675 Hardware Installation Guide for more information about RPS power connections. To locate this
documents, see the "Where to Go Next" section on page 34.
Va voltage = Vb voltage (greater than 0.25 V)
A-
A+
B+
B-
A- A-
A+ A+
B+ B+
B- B-
A- A-
Va Va
+ +
A+ A+
B+ B+
+ +
Vb Vb
B- B-
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