Juniper QFX5120 Series, Hardware Manual

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and running. You can install replacement power supplies in the two slots next to the fan modules without
powering off the switch or disrupting the switching function.
WARNING: A DC-powered QFX5120-48Y is intended for installation only in a restricted
access location.
NOTE: The battery returns of the DC power supply must be connected as an isolated DC return
(DC-I).
Before you begin connecting DC power to the switch:
•
Ensure that you have taken the necessary precautions to prevent electrostatic discharge (ESD) damage
(see “Prevention of Electrostatic Discharge Damage” on page 191 ).
•
Ensure that you have connected the switch chassis to earth ground.
CAUTION: Before you connect power to the switch, a licensed electrician must attach
a cable lug to the grounding and power cables that you supply. A cable with an
incorrectly attached lug can damage the switch (for example, by causing a short circuit).
To meet safety and electromagnetic interference (EMI) requirements and to ensure
proper operation, you must connect the chassis to earth ground before you connect
it to power. For installations that require a separate grounding conductor to the chassis,
use the protective earthing terminal on the switch chassis to connect to the earth
ground.
•
Install the power supply in the chassis.
Ensure that you have the following parts and tools available:
•
DC power source cables (14–16 AWG) with ring lug (Molex 190700069 or equivalent) (not provided)
•
Phillips (+) screwdriver, number 2 (not provided)
•
Multimeter (not provided)
To connect DC power to a QFX5120-48Y Switch:
1. Attach the grounding strap to your bare wrist and to a site ESD point.
2. Verify that the DC power cables are correctly labeled before making connections to the power supply.
In a typical power distribution scheme where the return is connected to chassis ground at the battery
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