Chapter 1 Product Overview
Switch Components
1-12
Catalyst 4900 Series Switch Installation Guide
78-18039-02
Figure 1-8 Airflow (Catalyst 4948-10GE shown)
There are four fans in the fan tray. If an individual fan fails, the other fans continue
to run. Sensors monitor the internal air temperatures. The number of fans in
operation and their speed varies according to the internal temperature for the
quietest operation possible. If the air temperature exceeds a desired threshold, the
environmental monitor displays warning messages.
Power Supplies
Note For complete power specifications for the switch, see Appendix A,
“Specifications.”
The Catalyst 4900 series switches have two redundant internal 300 W AC or 300
W
DC power supplies.
The internal power supplies have individual power cords and status LEDs (PS1
and PS2 on the front panel). There are also LEDs on the power supplies that show
status for the input (Input OK) and output (Output OK) currents. A power cord is
used to connect the power supplies to the site power source. There is a power
switch on the AC power supplies; AC power is present when a power cord is
plugged into a power supply and the switch is set to the On position. DC power
supplies do not have an on/off switch and do not provide a cable for connection
to a DC power source.
130085
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