Hot Spare Feature; Removing A Power Supply Unit Blank - Dell EMC PowerEdge T640 Installation And Service Manual

Hot spare feature

Your system supports the hot spare feature that significantly 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 load, thus operating at higher efficiency. 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 efficient 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, then the redundant PSU is switched to the active state.
• If the load on the active PSU falls below 20 percent, then the redundant PSU is switched to the sleep state.
You can configure the hot spare feature by using the iDRAC settings. For more information about iDRAC settings, see the Integrated Dell
Remote Access Controller User's Guide available at Dell.com/idracmanuals.

Removing a power supply unit blank

Prerequisite
Follow the safety guidelines listed in
Step
If you are installing a second PSU, remove the PSU blank in the bay by pulling the blank outward.
CAUTION: To ensure proper system cooling, the PSU blank must be installed in the second PSU bay in a non-redundant
configuration. Remove the PSU blank only if you are installing a second PSU.
Figure 31. Removing a power supply unit blank
Next step
Install the second PSU.
Related link
Installing a power supply unit
Safety instructions.
Installing and removing system components 83