Junos OS

Colleagues, help to deal with such an error :

show chassis alarms

1 alarms currently active
Alarm time Class Description

2007-01-08 15:10:11 EET Major PEM Invalid AC Configuration

show chassis power

PEM 0:
State: Online
AC input: OK (1 feed expected, 1 feed connected)
Capacity: 2050 W (maximum 2050 W)
DC output: 58 W (zone 0, 1 A at 58 V, 2% of capacity)

PEM 1:
State: Empty
Input: Absent

PEM 2:
State: Online
AC input: OK (1 feed expected, 1 feed connected)
Capacity: 2050 W (maximum 2050 W)
DC output: 114 W (zone 0, 2 A at 57 V, 5% of capacity)

PEM 3:
State: Empty
Input: Absent

System:
Zone 0:
Capacity: 4100 W (maximum 4100 W)
Allocated power: 480 W (3620 W remaining)
Actual usage: 172 W
Total system capacity: 4100 W (maximum 4100 W)
Total remaining power: 3620 W

show chassis hardware

Hardware inventory:
Item Version Part number Serial number Description
Chassis JN112E0E6AFB MX480
Midplane REV 05 710-017414 TR7671 MX480 Midplane
FPM Board REV 02 710-017254 WW3758 Front Panel Display
PEM 0 Rev 01 740-063046 QCS1829U0UB PS 1.4-2.52kW; 90-264V AC in
PEM 2 Rev 01 740-063046 QCS1829U0U6 PS 1.4-2.52kW; 90-264V AC in
Routing Engine 0 REV 07 740-013063 9009010152 RE-S-2000
Routing Engine 1 REV 07 740-013063 9009010146 RE-S-2000
CB 0 REV 03 710-021523 WV7436 MX SCB
CB 1 REV 03 710-021523 WV9131 MX SCB
FPC 0 REV 38 750-028467 ABCK0701 MPC 3D 16x 10GE
CPU
Fan Tray Enhanced Left Fan Tray

JunOS - version 16.2R2.8 

The mx480 requires 4 power supplies for full redundancy.  If you only have two supplies then they go into slots 0 & 1 to fully power the chassis in both power zones.

https://www.juniper.net/documentation/en_US/release-independent/junos/topics/topic-map/mx480-connecting-power.html

Many thanks !

Hi 

 The alarm is due to PEMs are in PEM0 and PEM2, from documentation they should be in PEM0 and PEM1.
https://www.juniper.net/documentation/en_US/release-independent/junos/topics/concept/power-supply-mx240-ac.html
  In the low-line (110 V) AC power configuration, the MX240 router contains either two AC power supplies (nonredundant), located horizontally at the rear of the chassis in slots PEM0 and PEM1 (left to right); or four AC power supplies (redundant), located in slots PEM0 through PEM3 (left to right). The low-line configuration requires two power supplies, and the third and fourth power supplies provide redundancy. Each AC power supply provides power to all components in the router. When two power supplies are present, they share power almost equally within a fully populated system. If one power supply in a redundant configuration fails or is removed, the remaining power supplies assume the entire electrical load without interruption. Two power supplies provide the maximum configuration with full power for as long as the router is operational.  In the high-line (220 V) AC power configuration, the MX240 router contains one or two AC power supplies, located horizontally at the rear of the chassis in slots PEM0 and PEM2 (left to right). The high-line configuration requires one power supply, with the second power supply providing redundancy. Each AC power supply provides power to all components in the router. When two power supplies are present, they share power almost equally within a fully populated system. If one power supply fails or is removed, the remaining power supply assumes the entire electrical load without interruption. One power supply can provide the maximum configuration with full power for as long as the router is operational.

If this solves your problem, please mark this post as "Accepted Solution."

Hello,

the only thing I can find for this is the following:

https://www.juniper.net/documentation/en_US/junos/topics/topic-map/chassis-guide-tm-error-handling-alarms.html

"When two AC power supplies are installed, insert one power supply into an odd-numbered slot and the other power supply into an even-numbered slot."

Please try to move PEM 2 to PEM 1 (or PEM 3) slot and check if the alarm is cleared then

Hi AfroAmestigon,

MX480 has 2 zones (0 and 1) and there should be one PEM in each zone (MAX 2 supported) for router to be functional.

In your case you have inserted both the PEM's in zone 0 which is triggering the alarm.

NOTE: PEM slot  0  and 2,  1 and 3 are redunatant to each other. 

If this solves your problem, please mark this post as "Accepted Solution" so we can help others too

Kudos are appreciated too 🙂

Regards,

Nadeem