Figure 67: Ac Power Supply Module - Juniper MX2020 Hardware Manual

Copyright © 2015, Juniper Networks, Inc.
three-phase wye. The PSMs work with a single phase only. Each phase from the each of
the two feeds is distributed among one or two PSMs. This means up to six different
phases can come into the PDM and get distributed among nine AC PSMs. There are a
total of eighteen AC PSMs located at the rear of the chassis in slots
(bottom), and slots PSM9
through provide power to the lower fan trays (
PSM8
through , CB-REs in slot
0 9
through PSM17 provide power to the upper fan trays upper (
in slot through , CB-REs in slot
10 19
NOTE: The MX2020 systems configured for three-phase wye AC input power
must use only three-phase wye AC PDMs and AC PSMs. The systems
configured for three-phase delta AC input power must use three-phase delta
AC PDMs and AC PSMs. AC and DC PSMs or PDMs must not be mixed within
a single system.
Up to nine PSMs may be connected in parallel per power subsystem to increase available
power for MPCs as needed and provide redundancy.
PSM.

Figure 67: AC Power Supply Module

The AC power system provides dual redundant feed. Each PSM takes in two AC feeds
and uses one of the two. Only one of the two feeds is active during power operation. Each
feed is a single phase AC system 200-240 VAC derived from a three-phase delta or wye
AC input system. Move the input mode DIP switch to the on or off position to determine
the power supply feeds (see
failure triggers the alarm LED on the craft interface. Each PDM has an LED per feed
indicating whether the feed is active or not, or whether the feed is connected properly,
see "MX2020 AC Power Subsystem Electrical Specifications" on page
Chapter 13: AC Power Requirements, Specifications, and Guidelines
through PSM17 (top) (left to right). The AC PSMs in slots
and , and SFBs in slot
0 1 0
and slot , and SFBs in slot
0 1
Figure 67 on page 159
Table 56 on page 160 and
through
PSM0
, , and upper ), and MPCs in slot
0 1 2
through . The PSMs in slots
7
2 , 3 , and lower 0 ), and MPCs
through .
0 7
shows the AC
Figure 68 on page 160). A PSM
158.
PSM8
PSM0
PSM9
159