Juniper MX2020 Hardware Manual page 116

Table 24: MX2020 DC Power Components (continued)
Component
DC Power Distribution Modules (240 V
China)
DC Power Supply Modules (PSMs)
Table 25: MX2020 AC Power Components
Component
AC power subsystem
Description
In the DC PDM (240 V China) configuration, each subsystem provides
N+1 PSM redundancy along with N+N feed redundancy. The power feeds
from different sources need to be connected to different PDMs. If feeds
that connect to one PDM fail in a redundant configuration, the other feed
will provide full power. You can install a total of four PDMs into a router.
Each DC PDM (240 V China) operates with nine feeds.
The MX2020 DC PSMs (-48 V and 240 V China) are hot-removable and
hot-insertable. The DC PSMs are a dual redundant feed (INP0 and INP1).
To provide feed redundancy, you can connect each DC PSM to two
separate feeds from different sources. When both input feeds are present,
power is drawn from the feed supplying higher DC voltage. You can set
these feeds by using the input mode DIP switch located on the DC PSM
(see "MX2020DC Power Supply Module (-48 V) Description" on page
There are two PDMs per power subsystem capable of carrying seven
feeds or nine feeds each. The 240 V China PDM has nine feeds. Each DC
PSM is capable of delivering 2500 W of power if -48 V/80 A is applied
to the -48 V PSM, and 240 V/16 A is applied to the China 240 VDC PSM.
Description
The MX2020 supports connection of a single-phase or three-phase (delta
or wye) AC power system. In the three-phase power systems, the AC
power going to the PSMs is split into three individual phases (wye) or a
pair of phases (delta). Each PSM works on a single phase; therefore, the
power system works independent of the type of AC feed connected. You
can connect one or two AC feeds, depending on the power system
configuration (number of PSMs, redundancy, and so on). Each phase from
each of the two feeds is distributed among one or two PSMs. One feed
has each phase going to two PSMs, and the other feed has each phase
going to a single PSM.
The single-phase AC PDM provides an AC input connection from the
single-phase AC power source, and also provides an input power interface
to the PSM through a system power midplane.
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