Juniper QFX Series Hardware Guide

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 158).
•
Ensure that you have connected the switch chassis to earth ground.
CAUTION: Before you connect power to the switch, a licensed electrician
must attacha cablelug 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. For instructions on
connecting earthground,see “Connectingthe QFX5110 to GroundingCable”
on page 92.
•
Install the power supply in the chassis. For instructions on installing a power supply in
a QFX5110, see “Installing a Power Supply in a QFX5110” on page 111.
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 QFX5110:
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 plant, you can use a multimeter to verify the resistance
of the –48V and RTN DC cables to chassis ground:
•
The cable with very low resistance (indicating a closed circuit) to chassis ground is
positive (+) and will be installed on the V+ (return) DC power input terminal.
•
The cable with very high resistance (indicating an open circuit) to chassis ground
is negative (–) and will be installed on the V– (input) DC power input terminal.
Copyright © 2019, Juniper Networks, Inc.98
QFX5110 Switch Hardware Guide

Juniper QFX Series Specifications

General

Category	Switch
Series	QFX
Form Factor	1U, 2U, and modular chassis options
Power Supply	Redundant, hot-swappable power supplies
Cooling	hot-swappable fans
Virtual Chassis	Supported on certain models
Typical Use	Data center, cloud
Operating System	Junos OS
Management	CLI
Key Features	High performance, low latency, automation
Latency	Sub-microsecond latency
Port Density	Varies by model (e.g., QFX5100: up to 48x10GbE + 6x40GbE)