With two Power Supplies being available, the server still goes into sleep mode when the primary power supply fails.
The time lag for the second power supply to cut in puts the server into sleep or shutdown mode.
To configure the power supply options:
In the iDRAC Web interface, go to Overview > Server > Power Thermal > Power Configuration > Power Configuration.
The Power Configuration page is displayed.
Under Power Supply Options, select the required options.
Click Apply. The power supply options are configured.