Figure 126: Dc Power Supply - Juniper QFabric QFX3000-G Hardware Documentation

PoE Power Budget and AC Power Supplies
Copyright © 2018, Juniper Networks, Inc.
NOTE: The DC power supply in the switch does not support Power over
Ethernet (PoE); you can use either an external power injector or an AC power
supply to supply power to PoE devices that you connect to the switch.
NOTE: The DC power supply in the switch has four terminals labeled A+, B+,
A–, and B– (see
cables labeled positive (+) and negative (–). The DC power supplies are
shipped with jumpers from A+ input to B+ input tied together and jumpers
from A– input to B– input tied together.
NOTE: The A+ and B+ terminals are referred to as +RTN and A– and B–
terminals are referred to as –48 V in
on page 367 and

Figure 126: DC Power Supply

To avoid electrical injury, follow instructions in Installing a Power Supply in an EX3200
Switch and Removing a Power Supply from an EX3200 Switch or
in an EX4200 Switch" on page 697
on page 695 carefully.
The PoE power budget for a PoE switch model is determined by the capacity of its power
supply. For EX4200 switches, the capacity of the power supply provided with a PoE
model is sufficient to supply each PoE-capable port with up to 15.4 W in compliance with
the IEEE 802.3af PoE standard.
the associated PoE power budgets for EX4200 switch models that support PoE.
Starting with Junos OS Release 11.1, EX4200 switches support enhanced PoE, a Juniper
Networks extension to the IEEE 802.3af PoE standard. Enhanced PoE permits up to 18.6
W per PoE port. Because the power supply provided with a switch is designed to supply
a maximum of 15.4 W per PoE port, if you connect a powered device that draws more
Figure 126 on page 191) for connecting DC power source
"DC Power Wiring Sequence Warning"
"DC Power Electrical Safety Guidelines" on page
or "Removing a Power Supply from an EX4200 Switch"
Table 57 on page 192 lists the power supply ratings, and
Chapter 8: EX4200 Overview
364.
"Installing a Power Supply
191