Juniper MX2020 Hardware Manual page 41

Figure 6: Power Distribution in a DC Base Power Subsystem
Figure 7 on page 15 illustrates how the power zones in the MX2020 optimized DC power subsystem
distribute power to FRUs
Figure 7: Power Distribution in an Optimized DC Power Subsystem
DC PSMs—The MX2020 DC PSMs (-48 V) and DC PSMs (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
Description" on page 112).
DC PDMs (-48 V) There are two PDMs per power subsystem capable of carrying seven feeds or nine
feeds each. You can install a total of four PDMs into a router. Each DC PDM operates with seven feeds
or nine feeds of either a 60-A or 80-A current limit. The capacity of these feeds is relayed to system
software through a switch located on the DC PDM. In a redundant configuration, the seven-feed DC
PDMs support a total of fourteen 60-A or 80-A feeds, and the nine-feed DC PDMs support a total of
eighteen 60-A or 80-A feeds. Each DC PSM is capable of delivering 2500 W of power if 80-A feeds are
connected. In the DC 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.
"MX2020DC Power Supply Module (-48 V)
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