Fans - Juniper E SERIES BROADBAND SERVICES ROUTERS 11.3.X - ERX HARDWARE GUIDE REV 26-9-2010 Hardware Manual

Fans

Copyright © 2010, Juniper Networks, Inc.
(See Figure 5 on page 8 and Figure 6 on page 8.) The power supplies convert AC power
to internal –48 V redundant DC feeds that are then distributed through the router.
Forced air-cooling keeps the temperature of the E Series modules and components within
normal operating limits. In ERX14xx models, six cooling fans are located in a tray at the
top of the router (Figure 1 on page 5). In ERX7xx models, four cooling fans are located
in a tray on one side of the router (Figure 3 on page 6). In the ERX310 router, two cooling
fans are located in a tray on one side of the router (Figure 5 on page 8).
The system monitors the temperature of each module. If the temperature of a module
exceeds the maximum limit, the system immediately goes into thermal protection mode
and the modules are powered off. The ERX system controller enters a low power mode,
keeps the modules in a power-off condition, and does not respond to any management
interface commands. For information about troubleshooting high operating temperatures,
see "Troubleshooting" on page 95.
In ERX7xx and ERX14xx models, the fan tray has two redundant converters that power
the fans (for the ERX14xx models, a –24 V, 50 W converter; for the ERX7xx models, a
–12 V, 15 W converter). If one converter fails, the other takes over. The ERX310 router
does not have redundant converters.
For all E Series routers, the system software reports an alarm if any of the fans or
converters fail.
Chapter 1: ERX Overview
17