HP ProLiant DL20 Gen10 User Manual page 88

12. Make sure the -48V DC power source is off or the PDU breaker is in the off position.
13. Connect the power cord to the -48V DC power source or PDU.
14. Turn on the -48V power source or switch the PDU breaker to the on position to supply -48V to the power supply.
15. Make sure that the power supply LED is green.
The installation is complete.
Installing a hot-plug DC power supply 88