Juniper EX9208, Hardware Manual, Page: 71 / 396

This topic describes the DC power supplies in EX9208 switches:
•
DC Power Supply Description on page 47
•
DC Power Supply Configurations on page 47
DC Power Supply Description
The DC power supplies in EX9000 switches are hot-insertable and hot-removable
field-replaceable units (FRUs).
You can install either two or four DC power supplies in an EX9208 switch. Power supplies
are installed in the rear of the chassis in slots
PEM0 through PEM3 (left to right).
Each DC power supply weighs approximately 6.2 lb (2.81 kg) and consists of one DC input
(–48 VDC and return), one 70 A (–48 VDC) circuit breaker, a fan, and LEDs to monitor
the status of the power supply. See
Figure 23 on page 47 .
Each DC power supply has a single DC input (–48 VDC and return) that requires a
dedicated circuit breaker. We recommend you provision 60 A or 75 A per feed, depending
on the selected DIP switch setting. If you plan to operate a maximally configured
DC-powered switch with DC power supplies, we recommend that you use a dedicated
customer site circuit breaker rated for 70 A (–48 VDC) minimum, or as required by local
code.
If you plan to operate a DC-powered switch at less than the maximum configuration, we
recommend that you provision a circuit breaker according to respective National Electrical
Code and customer site internal standards to maintain proper level of protection for the
current specified above or each DC power supply rated for at least 125% of the continuous
current that the system draws at –48 VDC.
Figure 23: DC Power Supply for an EX9208 Switch
DC Power Supply Configurations
In the DC power configuration, the EX9208 switch contains either two or four DC power
supplies located at the rear of the chassis in slots
PEM0 through PEM3 (left to right). You
can upgrade your DC power system from two to four power supplies.
47 Copyright © 2017, Juniper Networks, Inc.
Chapter 4: Power Supplies