Cisco 3825 Series Quick Start Manual - Page 22

Browse online or download pdf Quick Start Manual for Network Router Cisco 3825 Series. Cisco 3825 Series 40 pages. Integrated services routers
Also for Cisco 3825 Series: Installation And Upgrades (20 pages), Non Proprietary Security Policy (30 pages), Quick Start Manual (38 pages)

Print Page
Cisco 3825 Series Quick Start Manual
Figure 16
Connecting to One Source Only—Source A or Source B
A-
+
A+
B+
B-
In Figure 17, source A and source B share common negative terminal connections.
Figure 17
Connecting Source A and Source B with Common Negative Terminals
Va
+
+
Vb
In Figure 18, source A and source B share common positive terminal connections. This is allowed only if Va equals Vb (within
0.25 V).
Caution
When connecting source A and source B with common positive terminals, if source A and source B voltages are
unequal by more than 0.25 V, the higher-voltage source can discharge into the lower-voltage source through the A-
and B- input terminals. Excessive discharging currents through these terminals can cause one or both of the dual
input DC power supply's internal A- or B- fuses to open, resulting in lack of redundancy or system failure. When
source A and source B are within 0.25 V, discharge current is minimal.
Note
When source A and source B are wired with common negative terminals, as in Figure 17, discharging does not occur
and there is no restriction requiring that source A and source B voltages be equal.
22
+
A-
A+
B+
B-
A-
A+
B+
B-