Figure 5: Power Distribution From Each Power Subsystem To The Frus; Figure 6: Dc Power Subsystem Feed Redundancy - Juniper MX2020 Hardware Manual

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the chassis, and two fan trays (one for each zone). Specifically, each power subsystem
has enough power delivery capacity to power ten line card slots, three fan trays, two
CB-REs, and eight SFBs. There are nine DC power supply modules (PSMs), and two
DC power distribution modules (PDMs) in each subsystem. This means, if one power
subsystem stops functioning for any reason, only the MPCs will stop functioning, but
the router will continue functioning, (see

Figure 5: Power Distribution from Each Power Subsystem to the FRUs

Power
Available power
zone 1
20 KW
Available power Power
20 KW zone 0
DC power feed redundancy—The MX2020 router subsystem is feed redundant. Each
PSM can be connected to two separate feeds from different sources that are used to
provide feed redundancy. There are two PDMs per power subsystem that carry nine
feeds each. Users should connect feeds from one power source to one PDM and feeds
from the other power source to the second PDM of the power subsystem, (see
Figure 6 on page 13).

Figure 6: DC Power Subsystem Feed Redundancy

PDM 1
(feed B)
PSM PSM
0 1
PDM 0
(feed A)
Each PSM has a set of two DIP switches located on the faceplate. These DIP switches
are used to indicate whether a user wants to connect one feed to the power subsystem,
two feeds, or none. These DIP switches provide critical information to the power
management subsystem to help generate alarms in case of a feed failure or a wrong
connection. Each PDM has an LED per feed indicating whether the feed is active or not,
or whether the feed is connected properly. See
Description" on page 96.
AC power subsystem—The MX2020 supports connection of a three-phase AC power
system. There are two types of three-phase power systems: the three-phase delta
Chapter 2: System Overview and Architecture
Figure 5 on page 13).
LC 10-19
Available power: 14.5 KW
fan tray 3
SFB 0-7, CB0,
Available power: 5.5 KW from zone 1
CB1, fan tray 0,
Available power: 5.5 KW from zone 0
fan tray 2
LC 0-9
Available power: 14.5 KW
fan tray 1
PSM
8
"MX2020 DC Power Supply Module
13