Juniper QFX3500, Hardware Documentation

Page: 103 / 669

Power Supplies
EX4300 switches except EX4300-48MP and EX4300-48MP-S switches support AC or DC power supplies
with different airflow directions. EX4300-48MP and EX4300-48MP-S switches support only AC power
supplies with front-to-back airflow. Power supplies for the EX4300 switch are fully redundant, load-sharing,
and hot-removable and hot-insertable FRUs. All the EX4300 switch models except EX4300-24T-S,
EX4300-24P-S, EX4300-32F-S, EX4300-48T-S, EX4300-48P-S, and EX4300-48MP-S switches are shipped
with one power supply preinstalled in the rear panel of the switches. EX4300-24T-S, EX4300-24P-S,
EX4300-32F-S, EX4300-48T-S, EX4300-48P-S, and EX4300-48MP-S switches are not shipped with
preinstalled power supplies; you must order the power supplies separately.
Each power supply has a label—AIR IN (AFI) or AIR OUT (AFO)—on the faceplate of the power supply
that indicates the direction of airflow. AIR IN (AFI) labels indicate back-to-front airflow while AIR OUT
(AFO) labels indicate front-to-back airflow.
Table 10 on page 79 lists the AC and DC power supplies used in EX4300 switches and the direction of
airflow in them.
Table 10: Airflow Direction in Power Supplies for EX4300 Switches
Direction of Airflow Label on Power Supply
Power Supply
Rating
Back-to-front—that is, air intake to cool the
chassis is through the vents on the rear panel
of the chassis and hot air exhausts through
the vents on the front panel of the chassis.
AIR IN (AFI) 350 W AC
Front-to-back—that is, air intake to cool the
chassis is through the vents on the front panel
of the chassis and hot air exhausts through
the vents on the rear panel of the chassis.
AIR OUT (AFO) 350 W AC
Back-to-front—that is, air intake to cool the
chassis is through the vents on the rear panel
of the chassis and hot air exhausts through
the vents on the front panel of the chassis.
AIR IN (AFI) 550 W DC
Front-to-back—that is, air intake to cool the
chassis is through the vents on the front panel
of the chassis and hot air exhausts through
the vents on the rear panel of the chassis.
AIR OUT (AFO) 550 W DC
79