Juniper MX240 Hardware Manual page 435

Each High Capacity AC or DC power supply accepts two AC or DC feeds in two unique AC or DC
receptacles. It is possible to operate with one feed, but there is a reduction in the power supply output.
The DIP switch must be set according to the number of AC or DC feeds that are present for the power
supply. Refer to Figure 142 on page 439
Figure 142: MX240 DC High-Capacity Power Supply Input Mode Switch
Position – 0 indicates that only one AC or DC feed is provided.
Position – 1 indicates that two AC or DC feeds are provided.
To check the DIP switch position:
1. Issue the show chassis power command and check to see how many feeds are connected. The following
example shows there are two AC input feeds connected for PEM 0 and one AC input feed connected
for PEM 1. This indicates that the DIP switch for PEM 0 is in position 1 and the DIP switch for PEM 1
is in position 0. These are the proper settings.
# run show chassis power
PEM 0:
State: Online
AC input: OK (2 feed expected, 2 feed connected)
Capacity: 4100 W (maximum 4100 W)
DC output: 855 W (zone 0, 15 A at 57 V, 20% of capacity)
PEM 1:
State: Online
AC input: OK (1 feed expected, 1 feed connected)
Capacity: 1700 W (maximum 4100 W)
DC output: 969 W (zone 1, 17 A at 57 V, 57% of capacity)
2. Issue the show chassis alarms command to see if there are any active alarms on the DIP switch:
> show chassis alarms
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