Ex9253 Cooling System - Juniper EX9253 Hardware Manual

two high line power supplies or three low line must be installed in the switch for non-redundant
operation. In a redundant configuration, if one power supply fails or is removed, the remaining power
supplies assume the entire electrical load without interruption. In a base configuration, if one power
supply fails or is removed, one of the line cards is disabled. See
27.
• Cooling system-The cooling system consists of four fan trays and an air filter unit. Each fan tray
contains two counter-rotating fans. The fan trays are installed on the rear panel of the chassis. A fully
configured switch needs all the four fan trays to operate normal. In the event of any fan failure, the
fan tray with the faulty fan must be replaced immediately. You cannot replace a single fan. If one or
more fans fail, you must replace the entire fan tray. Under normal operating conditions, the fans in
the fan trays run at less than full speed. If a fan tray fails or the ambient temperature rises above a
threshold, the speed of the remaining fan trays is automatically adjusted to keep the temperature
within the acceptable range. If the ambient maximum temperature specification is exceeded and the
system cannot be adequately cooled, the Routing Engine shuts down the line card that cannot be
cooled adequately is disabled. If the fire threshold temperature is exceeded, the Routing Engine shuts
down the system by disabling output power from each power supply. See
on page 21.

EX9253 Cooling System

IN THIS SECTION
Fan Tray | 22
Air Filter Unit | 24
Fan Tray Status LEDs | 25
Cooling System in the Power Supplies | 26
Airflow Direction in the EX9253 Switch Chassis | 26
The cooling system in an EX9253 switch consists of four fan trays and an air filter unit. The cooling
system components work together to keep all switch components within the acceptable temperature
range.
"EX9253 Power System" on page
"EX9253 Cooling System"
21