Please find the below alarm description when the issue occur :
 

user@host> show chassis alarms no-forwarding
1 alarms currently active
Alarm time        Class Description

2023-07-26 12:37:10 IST Major FPC 0 PEM 0 Feed A not connected
 

Error in Syslog Messages :
 

Jul 27 13:22:21  alarmd[13301]: Alarm set: PS SFXPC id=419430475, color=RED, class=CHASSIS, reason=FPC 0 PEM 0 Feed A not connected.
 

Error in chassisd logs:
 

Jul 27 13:22:21 send: red alarm set, device Power Supply 0, reason FPC 0 PEM 0 Feed A not connected.

user@router> show chassis hardware | match "Power Supply" 
Power Supply 0  REV 1         TU8XCU1784R    Assy,Pwr Sply,DC Feed B, Airflow out ---- shows Feed B only connected 
 

Check for Feed A and Feed B connectivity for the DC Power cord

An issue with the Main Power source ; Power off of the DC input appliance inlet on the source power supply

Power Cord / incorrect voltage 

An issue with DC Power feed cable
 

Detailed Logs:
 

Jul 27 13:22:21 lcmd[13337]: LCMD_CNCTD: pvi_acx710_ipc_plugin_connect:423: Connected: state 2
Jul 27 13:22:21 lcmd[13337]: LCMD_FRU_COOKIE: pvi_acx710_ipc_plugin_send_chassis_info:519: Sent FRU information: cookie = 1
Jul 27 13:22:21 alarmd[13301]: Alarm set: PS SFXPC id=419430475, color=RED, class=CHASSIS, reason=FPC 0 PEM 0 Feed A not connected.
Jul 27 13:22:21 craftd[13302]: Receive FX craftd set alarm message: color: 1 class: 100 object: 75 slot: 0 silent: 0 short_reason=FPC long_reason=FPC 0 PEM 0 Feed A not connected. id=419430475 reason=419430400
Jul 27 13:22:21 craftd[13302]: Major alarm set, FPC 0 PEM 0 Feed A not connected.
Jul 27 13:22:21 Power Supply 0 added
Jul 27 13:22:21 hwdb: entry for pem 0 at slot 0 inserted
Jul 27 13:22:21 notify_fru_add: NULL kvpairs for Power Supply 0
Jul 27 13:22:21 pem_tvp_jdaf_info_update: psu_slot=0 input=1 expected=1 connected=0
Jul 27 13:22:21 pem_tvp_jdaf_info_update: psu_slot=0 input=2 expected=1 connected=1

Power Supply 0  REV 1         TU8XCU1784R    Assy,Pwr Sply,DC Feed B, Airflow out

The above logs denote that the Power supply for the Feed A is not connected. Since FPC is built in , It draws power from Feed A and Feed B

This above log may be seen when the Feed is not detecting power supply into it. This may be a cabling issue to detect the power being supplied when it is plugged in its slot or a missing input source to either of feed . It could also be an issue with external conditions like feeds, Power supply input source, Feed A/B slot issue.

Follow the steps below to overcome the error:

1. Verify which feed is missing -

user@host> show chassis hardware | match "Power Supply" 

Power Supply 0 REV 1     TU8XCU1784R  Assy,Pwr Sply,DC Feed B, Airflow out ---- shows Feed B only connected ​​​​​.
 

        2. Verify the DC Power is On

user@host> show chassis environment no-forwarding

Class Item              Status   Measurement

Power Power Supply 0         OK

As you can see below, the FPC is up since it has one working power supply, DC Feed that can take all the load.

user@host> show chassis fpc detail
Slot 0 information:
State                Online
Total CPU DRAM         255 MB
Temperature           47 degrees C / 116 degrees F
Start time             2023-07-26 12:36:44 IST
Uptime               1 hour, 1 minute, 42 seconds
 

3. System restarting continuously - With only one power source feed connected (power only on port A/B connection) .Wiggle that connection and the system will power cycle/ FPC will reset. It is strongly suggested that the power control module be replaced

Verify the following:

Verify Feed A and Feed B connectivity for the DC Power cord

Verify Power Cord / incorrect voltage 

Also, there may be situations when the alarm might vanish on its own. This is possible if the issue is transient in nature. In that case, ignore the occurrence and monitor the device so that the alarm does not re-occur. If the alarm occurs again, repeat the steps mentioned above in order to determine the faulty part.