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[ACX] PEM * overload/underload alarm seen on ACX-5448



Article ID: KB36899 KB Last Updated: 29 Apr 2021Version: 1.0

During normal operation of ACX5448/ACX5448-D/ACX5448-M platforms with AC PEMs, PEM 0 or 1 can report overload or underload alarms due to input feed exceeding the maximum limit.

This article explains that the alarm will automatically get cleared when the input feed is set to not exceed the maximum limit.


Minor alarms are set in the device by PEM 0 or 1 during normal operation of ACX5448/ACX5448-D/ACX5448-M platforms with AC PEMs.

root@router> show chassis alarms no-forwarding

2 alarms currently active
Alarm time               Class  Description
2021-03-31 10:36:24 GMT  Minor  PEM 1 overload/underload
2020-12-16 12:53:20 GMT  Minor  PEM 0 overload/underload

The alarm is set whenever the vin or input voltage is 240011mv for AC units. Alarm set/clear is also noticed in the chassisd logs.

>show log chassisd
chassisd.0.gz:Dec 25 11:48:36  PEM[0] Over voltage issue [vin: 240011mV, vout:12125mV]
chassisd.0.gz:Dec 25 11:48:36  send: yellow alarm set, device PEM 0, reason PEM 0 overload/underload
chassisd.0.gz:Dec 25 11:49:16  send: yellow alarm clear, device PEM 0, reason PEM 0 overload/underload



To resolve the issue, ensure that the input feed to PEM does not exceed 240V.

The alarm is cleared automatically when the input voltage (vin) does not exceed the max limit. For more information, refer to ACX5448, ACX5448-D, and ACX5448-M Power System.

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