Do not use interface module and power supply ejector handles to lift the chassis; using the handles to lift the
chassis can deform or damage the handles.
Caution
Preventing 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 like the Cisco
ASR 903 Router, which can have substantial current draw fluctuations due to bursty data traffic patterns.
Use the information in the
DC Power Specifications, on page 3
to estimate the power requirements and heat
dissipation of a Cisco ASR 903 Router based on a given configuration of the router. Determining power
requirements is useful for planning the power distribution system needed to support the router.
Power Connection Guidelines
This section provides guidelines for connecting the Cisco ASR 903 Router power supplies to the site power
source.
Never defeat the ground conductor or operate the equipment in the absence of a suitably installed ground
conductor. Contact the appropriate electrical inspection authority or an electrician if you are uncertain that
suitable grounding is available. Statement 213
Warning
The plug-socket combination must be accessible at all times because it serves as the main disconnecting
device. Statement 1019
Warning
This product requires short-circuit (overcurrent) protection, to be provided as part of the building installation.
Install only in accordance with national and local wiring regulations. Statement 1045
Warning
Guidelines for DC-Powered Systems
Basic guidelines for DC-powered systems include the following:
• Each chassis power supply should have its own dedicated input power source. The source must comply
with the safety extra-low voltage (SELV) requirements in the UL 60950, CSA 60950, EN 60950, and
IEC 60950 standards.
• 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.
Cisco ASR 903 and ASR 903U Aggregation Services Router Hardware Installation Guide
97
Installing the Cisco ASR 903 Router
Preventing Power Loss