Fuses; Cooling System; Figure 19: Circuit Breaker Box - Juniper Internet Router M160 Hardware Manual

Figure 19: Circuit Breaker Box

Fuses

The router uses fuses from the Cooper Bussman brand GMT series for the FPCs,
MCSs, PCGs, and SFMs. The fuses are located in a fuse box on the rear of the
midplane. When the fuse for a component blows, the component stops functioning
even though it is installed correctly and the power supplies are providing power to
the router. For more information, see "Blown Fuse Indicators" on page 211. For
fuse replacement instructions, see "Replacing a Fuse" on page 204.

Cooling System

The cooling system includes a fan tray and several impellers that draw room air into
the chassis to keep its internal temperature below a maximum acceptable level.
When the temperature is below the maximum, the fans and impellers function
at less than full speed. If the MCS detects that the temperature of a component
has exceeded the acceptable maximum—for example, because an impeller is
removed—it automatically increases the speed of the remaining impellers and fans
to reduce the temperature. The fans and impellers can function at the higher
speed indefinitely.
For more information about the cooling system, see the following sections:
Cooling System Components on page 40
Airflow through the Chassis on page 40
Hardware Component Overview
39
Cooling System