Dell PowerEdge R940 EMC Installation and Service Manual - Page 144

Power supply unit, Hot spare feature, Removing a power supply unit blank

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Figure 93. Installing optional IDSDM module Next steps 1. Install the MicroSD cards. NOTE: Reinstall the MicroSD cards into the same slots based on the labels you had marked on the cards during removal. 2. Follow the procedure listed in After working inside your system on page 66. Power supply unit 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 system 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 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 configure 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 blank Prerequisites Follow the safety guidelines listed in Safety instructions on page 65. 144 Installing and removing system components

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Figure 93. Installing optional IDSDM module
Next steps
1.
Install the MicroSD cards
.
NOTE:
Reinstall the MicroSD cards into the same slots based on the labels you had marked on the cards during
removal.
2.
Follow the procedure listed in
After working inside your system
on page 66.
Power supply unit
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 system 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 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 configure 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 blank
Prerequisites
Follow the safety guidelines listed in
Safety instructions
on page 65.
144
Installing and removing system components