Juniper Networks ERX Hardware 8 - Manual (Page 38)

ERX 8.0.x Hardware Guide
Fans
Forced air-cooling keeps the temperature of the E-series modules and components
within normal operating limits. In ERX-14xx models, six cooling fans are located
in a tray at the top of the router (Figure 1). In ERX-7xx models, four cooling fans
are located in a tray on one side of the router (Figure 3). In the ERX-310 router,
two cooling fans are located in a tray on one side of the router (Figure 5).
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 103.
In ERX-7xx and ERX–14xx models, the fan tray has two redundant converters
that power the fans (for the ERX-14xx models, a –24 V, 50 W converter; for the
ERX-7xx models, a –12 V, 15 W converter). If one converter fails, the other
takes over. The ERX-310 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.
20 Redundancy Features