Power Supply Fan; Load-Sharing Feature; Environmental Monitoring Feature - Cisco CAtalyst 4500 Series Installation Manual

Power Supplies

Power Supply Fan

Load-Sharing Feature

Note

Environmental Monitoring Feature

Catalyst 4500 Series Switches Installation Guide
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Each power supply has a built-in fan. Air enters the front of the power supply
(power-input end) and exits through the back. An air dam keeps the airflow
separate from the rest of the chassis, which is cooled by the system fan assembly.
When you install and turn on a second power supply on a Catalyst 4500 series
switch, it provides approximately one-half of the required power to the system. If
one power supply fails, the other power supply immediately assumes full power
to maintain uninterrupted system operation.
Load sharing works only when both power supplies in the chassis are the same
type.
When you install a redundant power supply, load sharing and fault tolerance are
enabled automatically; no additional software configuration is required.
With the environmental monitoring and reporting feature, you can keep your
system running by resolving adverse environmental conditions before loss of
operation.
The power supply monitors its own internal temperature and voltages. In the event
of excessive internal temperature, the power supply shuts down to prevent
damage. When the power supply returns to a safe operating temperature, it
restarts. If the power supply output voltage is not within the specified range, the
LED labeled OUTPUT FAIL will light. An instance of substantial output
overvoltage can shut down the power supply.
An instance of substantial input overvoltage (greater than –75 V DC continuous)
can damage the power supply input circuitry and can cause it to shut down
permanently.
Chapter 1 Product Overview
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