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Owners Manual

ManualsBrandsDell ManualsAX NodesEMC XC Core XC940 System
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NOTE: If two PSUs are used, they must be of the same maximum output power.
Hot spare feature
Your system supports the hot spare feature that signicantly reduces the power overhead associated with power supply unit (PSU)
redundancy.
When the hot spare feature is enabled, one of the redundant PSUs is switched to the sleep state. The active PSU supports 100 percent of
the system load, thus operating at higher eciency. The PSU in the sleep state monitors output voltage of the active PSU. If the output
voltage of the active PSU drops, the PSU in the sleep state returns to an active output state.
If having both PSUs active is more ecient than having one PSU in the sleep state, the active PSU can also activate the sleeping PSU.
The default PSU settings are as follows:
• If the load on the active PSU is more than 50 percent of PSU rated power wattage, then the redundant PSU is switched to the active
state.
• If the load on the active PSU falls below 20 percent of PSU rated power wattage, then the redundant PSU is switched to the sleep
state.
You can congure the hot spare feature by using the iDRAC settings. For more information, see the iDRAC User’s Guide available at
Dell.com/idracmanuals.
Removing a power supply unit
The procedure for removing AC and DC PSUs is identical.
Prerequisites
CAUTION
: The system needs one power supply unit (PSU) for normal operation. On a power-redundant system, remove and
replace only one PSU at a time in a system that is powered on.
1 Follow the safety guidelines listed in Safety instructions.
2 Disconnect the power cable from the power source and from the PSU you intend to remove, and then remove the cable from the
strap on the PSU handle.
3 Unlatch and lift the optional cable management arm if it interferes with the PSU removal.
For information about the cable management arm, see the system’s rack documentation at Dell.com/XCSeriesmanuals.
Step
Press the orange release latch and slide the PSU out of the system by using the PSU handle.
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Installing and removing system components