• The circuit must be protected by a dedicated two-pole circuit breaker. The circuit breaker should be sized
according to the power supply input rating and local or national code requirements.
• The circuit breaker is considered the disconnect device and should be easily accessible.
• The system ground is the power supply and chassis ground.
• Do not connect the DC return wire to the system frame or to the system-grounding equipment.
• Use the grounding lug to attach a wrist strap for ESD protection during servicing.
• Ensure the DC return is grounded at the source side.
Guidelines for AC-Powered Systems
Basic guidelines for AC-powered systems include the following:
• Each chassis power supply should have its own dedicated branch circuit.
• The circuit breaker should be sized according to the power supply input rating and local or national code
requirements.
• The AC power receptacles used to plug in the chassis must be the grounding type. The grounding
conductors that connect to the receptacles should connect to protective earth ground at the service
equipment.
Prevent Power Loss
Use the following guidelines to prevent power loss to the router:
• To prevent loss of input power, ensure that the total maximum load on each circuit supplying the power
supplies is within the current ratings of the wiring and breakers.
• In some systems, you can use an UPS to protect against power failures at your site. Avoid UPS types
that use ferroresonant technology. These UPS types can become unstable with systems such as the Cisco
ASR 920 Series Router, which can have substantial current-draw fluctuations due to bursty data traffic
patterns.
Determining power requirements is useful for planning the power distribution system needed to support the
router.
Activating a DC Power Supply
Perform the following procedure to activate a DC power supply:
Procedure
Step 1
Remove the tape from the circuit-breaker router handle, and restore power by moving the circuit-breaker
router handle to the On (|) position.
Step 2
Verify power supply operation by checking if the respective power supply front panel LED (PS0 or PS1) is
green.
Step 3
If the LEDs indicate a power problem, see the
Troubleshooting
section.
Step 4
If you are connecting a redundant DC power supply, repeat these steps for the second power source.
If you are connecting a redundant DC power supply, ensure that each power supply is connected
to a separate power source in order to prevent power loss in the event of a power failure.
Note
Installing the Router
43
Installing the Router
Guidelines for AC-Powered Systems
