Power supply unitsYour system supports 350 W AC redundant power supply units (PSUs).NOTE: If two PSUs are used, they must be of the same type and have the same maximum outputpower.When two identical PSUs are installed, the PSU configuration is redundant (1 + 1). In redundant mode,power is supplied to the system equally from both PSUs to maximize efficiency.When only one PSU is installed, the PSU configuration is non-redundant (1 + 0). Power is supplied to thesystem only by the single PSU.In a non-redundant configuration, install a PSU blank in the empty PSU slot.Hot spare featureYour system supports the hot spare feature that significantly reduces the power overhead associated withpower supply redundancy.When the hot spare feature is enabled, one of the redundant PSUs is switched to the sleep state. Theactive PSU supports 100% of the load, thus operating at higher efficiency. The PSU in the sleep statemonitors output voltage of the active PSU. If the output voltage of the active PSU drops, the PSU in thesleep 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 canalso activate the sleeping PSU.The default PSU settings are as follows:• If the load on the active PSU is more than 50%, then the redundant PSU is switched to the active state.• If the load on the active PSU falls below 20%, 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 iDRACsettings, see the Integrated Dell Remote Access Controller User’s Guide at Dell.com/idracmanuals.Removing a redundant power supply unitPrerequisitesCAUTION: Many repairs may only be done by a certified service technician. You should onlyperform troubleshooting and simple repairs as authorized in your product documentation, or asdirected by the online or telephone service and support team. Damage due to servicing that isnot authorized by Dell is not covered by your warranty. Read and follow the safety instructionsthat came with the product.CAUTION: The system requires one power supply for normal operation. On power-redundantsystems, remove and replace only one power supply at a time in a system that is powered on.1. Ensure that you follow the Safety instructions.2. Disconnect the power cable from the power source.3. Disconnect the power cable from the power supply unit (PSU) and remove the straps that bundleand secure the system cables.105
