Specifications

40 | Power Supplies
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The PSUs are in a single piece with the PSU fans (see Figure 5-1 ). You can replace the fan trays
individually, but you cannot replace the fans that are attached to the PSUs—if the fans attached to the
PSU fail, you must replace the entire PSU. For fan tray replacement procedures, refer to
Chapter 6, Fans .
WARNING: Prevent exposure and contact with hazardous voltages. Do not attempt to operate this system
with the safety cover removed.
CAUTION: Remove the power cable from the PSU prior to removing the PSU. Also, do not connect the power
cable before you insert the PSU in the chassis.
CAUTION: The DC PSU comes with a 6-8 inch power cord with a snap-in plug that attaches to the DC power
supply and screw terminals that attach to the main power. To ensure sufficient room, Dell Force10
recommends using a longer cable.
CAUTION: The power supply is marked + 48V -. Connect the + (plus sign) to the red cable on the 6-8 inch
cord; connect the - (minus sign) to the black cable on the 6-8 inch cord. BE SURE TO connect the RED cable
to RETURN and the BLACK cable to -48V.
NOTE: To comply with the GR-1089 Lightning Criteria for Equipment Interfacing with AC Power Ports, use an
external SPD at the AC input of the router.
Installing an AC or DC Power Supply
To install an AC or DC power supply, follow these steps:
NOTE: The PSU slides into the slot smoothly. Do not force a PSU into a slot as this may damage the PSU or
the S4820T chassis.
NOTE: If you use a single PSU, you must install a blank plate in the other PSU slot. Dell Force10
recommends using power supply 1 (PSU1) as the blank plate slot.
Replacing an AC or DC Power Supply
NOTE: The PSU slides into the slot smoothly. Do not force a PSU into a slot as this may damage the PSU or
the S4820T chassis.
NOTE: If a PSU fails, you must completely replace it. There are no field servicable components in the PSU. To
request a hardware replacement, refer to Chapter 9, Technical Support .
NOTE: If you use a single PSU, you must install a blank plate in the other PSU slot. Dell Force10
recommends using power supply 1 (PSU1) as the blank plate slot
Step Task
1 Take the PSU out of the shipping box.
2 Use the grab handle to slide the PSU into the power supply bay.
3 Tighten the securing screw at the top of the PSU.
4 Attach the power cables.
NOTE: The S4820T powers up as soon as the cables are connected between the power supply
and the power source.