Hello, everyone!
I would like to share with you an issue about POWER_FAIL alarm on multiple PIU board housed in an OptiX OSN 8800 T32 + 2 x OSN8000 UPS node.
Description:
O&M staff monitor at NCE the occurrence of multiple POWER_FAIL alarm in the following PIU boards:
Subrack 1 // PIU // Slots 39 & 40 [OSN 8800 T32]
Subrack 2 // PIU // Slot 17 [OSN 8800 UPS]
Subrack 3 // PIU // Slot 17 [OSN 8800 UPS]
These alarms appear on NE during 12 minutes and then clear.
Power supply failure. This alarm is generated when the power supply of a board becomes abnormal. For example, there is overvoltage or undervoltage of the power supply, or the battery on the system control board has no charge.
The power distribution and redundancy showed as below:
Impact:
The normal operation of the equipments (OSN 8800 T32 + 2 x OSN 8800 UPS) is not affected in this case because the failure only occurs in one of both external input -48V power supply (section A).
Possible causes:
Cause 1: If this alarm is reported by the system control board, the battery of the system control and communication board is abnormal (the value of parameter 1 of this alarm is 0x05).
Cause 2: If this alarm is reported by the PIU board, the input voltage of the subrack is abnormal because the power supply module is faulty (the value of parameter 1 of this alarm is 0x3d or 0x3f).
Cause 3: If this alarm is reported by the PIU or CRPC board, the power supply module of the board fails or is aging (the value of parameter 1 of this alarm may be any value except 0x05).
Cause 4: If the system control board reports this alarm (Parameter 1 is 0x99), the user configuration data within 30 minutes before the power failure of the system control board is lost.
In our case, the POWER_FAIL alarms are reported by the PIU boards and the value of parameter 1 of these alarms are 0x3d as below. Therefore, it is Cause 2.
Procedure:
Cause 2: If this alarm is reported by the PIU board, the input voltage of the subrack is abnormal because the power supply module is faulty (the value of parameter 1 of this alarm is 0x3d or 0x3f).
1) Check whether the switch on the DC power distribution box of the cabinet is ON. If it is not, turn it to ON.
2) Use a multimeter to check whether the voltage of the external input power supply is within the permitted range (the permitted range for the voltage of the working power supply for OptiX optical transmission equipment is -72 V to -40 V). If the voltage is not within the permitted range, check whether the power supply of the equipment room is normal.
3) If the voltage of the external input power supply is within the permitted range but the alarm persists, the power switch on the DC power distribution box may be faulty. In this case, replace the switch. For details, see "Replacing the Power Switch on the DC Power Distribution Box".
4) If the alarm persists, the PIU board is faulty. Replacing the PIU Board.
Solution:
After it was said that these alarms appear on NE during 12 minutes and then clear.
Therefore, the main suspicion pointed a failure in the power supply system of the equipment room.
Finally, because the NE was installed in a DPC (Data Protection Center), the O&M staff of this DPC were called and confirmed that there was a power supply outage for 12 minutes in the power supply system that supplied power to section A of the OSN 8800 cabinet.
Conclusion:
Among all the conclusions that could be drawn about the previous issue, we are going to highlight the importance of Power Redundancy:
"Two PIU boards or two APIU boards in hot backup mode supply power to one subrack at the same time. When one of the boards becomes faulty, the other board continues to supply power to the subrack to ensure that the subrack can still function properly".
That's all, I welcome everyone to leave a message and exchange in the comment area!
Thank you!
References:
- HedEx
BR
