Cisco Systems 4500 manual Power Supply Fan, Load-Sharing Feature, Environmental Monitoring Feature

Chapter 1 Product Overview

Power Supplies

Power Supply Fan

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.

Load-Sharing Feature

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.

Note 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.

Environmental Monitoring Feature

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.

	Catalyst 4500 Series Switches Installation Guide
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