Replace a Power Supply

Pre-Installation Requirements

You need the following tools and materials to replace a power supply:

• Thermal protective gloves
• AC power cord, if you are not re-using the cord from the removed power supply

Remove a Power Supply

Caution

Disconnect the AC power cord from the wall outlet and from the power supply before removing an AC power supply. Ensure that the DC circuit is de-energized before removing a DC power supply.

Use the following instructions to remove a power supply.

1. Attach an ESD-preventive wrist strap to your bare wrist and connect the metal end to an appropriate ground point on the rack.
   

   Caution

   Power supplies can become very hot during operation. Wear thermal protective gloves when you remove a power supply from an operating switch.
2. Note the orientation and the airflow direction of the installed power supply, and the location of the latching tab on the power supply.
3. Push the latching tab toward the power supply handle and pull outward on the handle to disengage the power supply internal connectors.

   

   Remove a Power Supply

   

   

   Note

   If you are not installing a replacement power supply, install a cover over the unoccupied power supply bay. Unoccupied bays must always be covered to maintain proper system ventilation and EMI levels.

Replace or Install a Power Supply

Use the following instructions to replace or install a power supply.

1. Attach an ESD-preventive wrist strap to your bare wrist and connect the metal end to an appropriate ground point on the rack.
2. If necessary, remove a blank panel from the back of the switch.
3. Ensure that the orientation of the power supply is correct, and that the new power supply's airflow direction (front-to-back or back-to-front) is compatible with the installed fan modules and any other installed power supplies.
4. Carefully slide the power supply all the way into the power supply slot.

   

   Install a Power Supply

   

5. Push the power supply in until the latch snaps into place.

   Do not slam the power supply into the switch.

   

   Note

   Be sure to install a cover over any unoccupied power supply slots. Unoccupied power supply slots must always be covered to maintain proper system ventilation and EMI levels.

To install or replace a second power supply repeat this procedure.

Connect a DC Power Supply to the Source Voltage

The DC power connection at your facility must be made by a qualified electrician, following these instructions.

Warning

Always make sure that the DC circuit is de-energized before connecting or disconnecting the DC power cables on the DC power supply

Caution

Provide proper connection and strain relief on the DC power cables in accordance with all local and national electrical codes.

1. Verify that the DC circuit is de-energized.
2. Attach an ESD-preventive wrist strap to your bare wrist and connect the metal end to an appropriate ground point on the rack.
3. Position the DC power cable connector so that the wide, flat side is closest to the fan, as shown in ../Universal_Hardware_Common/remove_and_replace_power_supplies.shtml#concept-2678__FIG_MYK_D4L_NZB. The DC power cable connector can only connect to the power supply one way.

   

   Connecting the DC Power Cord

   

4. Tighten the two thumb screws to secure the DC power connector in place.
5. The installation electrician connects the other end of the power cord to the building power system.
   

   Warning

   Before installing, be sure to connect the chassis ground wire before you connect any power cables.
   

   Warning

   Before removing, be sure to disconnect the ground wire after you disconnect all power cables
   1. Connect the ring terminal of the yellow and green ground wire to a known reliable earth ground point at your site.

      

      DC Power Cable

      

      Use the following for building the wire harness:

      Cable Connector	Wire Color
      Pin 1	Yellow/Green	GRD
      Pin 2	Black	-48V
      Pin 3	Red	RTN

   2. Connect the ring terminal of the red RTN power cable to the positive terminal of the DC power source, and connect the ring terminal of the black -48V power cable to the negative terminal of the DC power source.
6. Repeat these steps for each power supply.

Leave the ESD strap permanently connected to the rack, so that the strap is always available when you need to handle ESD-sensitive components.