Juniper M320 Hardware Manual page 149

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Copyright © 2010, Juniper Networks, Inc.
Temperature
DC input
Load
48.0 V input
48.0 V fan supply
8.0 V bias
5.0 V bias
NOTE: The current sharing between PEMs relies on equal voltages at the
input terminals of the PEMs. The M320 system power is divided into two
load zones. One load zone consists of PEM0 and PEM2, and the other load
zone consists of PEM1 and PEM3. Load sharing occurs only between the
PEMs of each load zone (PEM0 and PEM2 or PEM1 and PEM3). Therefore,
those two PEMs voltages should be equal for current sharing. However, if
the voltages do not match, the router operates normally as long as the DC
input voltages are within the operating range provided in "M320 DC Power
Electrical Specifications" on page 255. See "M320 DC Power Cable
Specifications" on page 257 for a typical DC source cabling arrangement.
Make sure that the power and grounding cables are arranged so that they do not
obstruct access to other router components.
Routinely check the
OUTPUT OK
faceplates and the craft interface. If these output status LEDs are lit, the power supplies
are functioning normally. For more information about the power supply LEDs, see
"M320 Power System Description" on page 33.
Check the red and yellow alarm LEDs and the LED display on the craft interface. Power
supply failure or removal triggers an alarm that causes one or both of the LEDs to light
and an error message to appear on the LED display. You can display the associated
error messages by issuing the following CLI command:
user@host> show chassis alarms
For a list of possible alarm messages, see "M320 Chassis and Interface Alarm Messages"
on page 127.
The power supplies require an unobstructed airflow at both the front and rear of the
chassis. Periodically check the site to ensure that both the air intake at the bottom
front of the chassis and the exhaust from the power supply faceplates are unobstructed.
Periodically inspect the site to ensure that the grounding and power cables connected
to the router are securely in place and that no moisture is accumulating near the router.
To review grounding and site wiring requirements for the router, see "M320 Site
Preparation Checklist Requirements" on page 41.
Troubleshooting the M320 Power System on page 132
Replacing M320 Power System Components on page 193
Site Electrical Wiring Guidelines for M Series, MX Series, and T Series Routers on page 249
Chapter 11: Maintaining M320 Router Hardware Components
OK
OK
Less than 20 percent
54219 mV
49002 mV
8485 mV
4996 mV
and the status LEDs on the power supply
POWER OK
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