Dell PowerEdge R630 Owner's Manual page 26

Convention Power indicator
pattern
E Not lit
Figure 12. DC PSU status indicator
1. DC PSU status indicator
Table 15. DC PSU status indicators
Convention Power indicator
pattern
A Green
B Flashing green
C Flashing amber
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Condition
CAUTION: AC PSUs support both 220 V and 110 V input
voltages with the exception of Titanium PSUs, which support
only 220 V. When two identical PSUs receive different input
voltages, they can output different wattages, and trigger a
mismatch.
CAUTION: If two PSUs are used, they must be of the same type
and have the same maximum output power.
CAUTION: Combining AC and DC PSUs is not supported and
triggers a mismatch.
Power is not connected.
Condition
A valid power source is connected to the PSU and that the PSU is
operational.
When hot-adding a PSU, the PSU indicator flashes green. This
indicates that there is a PSU mismatch with respect to efficiency,
feature set, health status, and supported voltage. Replace the PSU
with a PSU that matches the capacity of the other installed PSU.
Indicates a problem with the PSU.