Cisco 3825 Series Manual de início rápido - Página 21

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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

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.

A-

A+

B+

B-

A-

A+

B+

B-