This article explains the syslog message "PEM power status has changed, run power budget again" observed in chassisd and ways to mitigate them.

Jun 28 07:06:23 PEM power status has changed, run power budget again

Jun 28 07:06:23 [Alarm SET] Object 75 reason 28 Device FRU PEM 2, reason PEM 2 No Power(PEM 2 Not Powered), color 2, slot 0 Alarm id 1258299420

Jun 28 07:06:23 send: yellow alarm set, device FRU PEM 2, reason PEM 2 Not Powered

Jun 28 07:06:29 PEM power status has changed, run power budget again

Jun 28 07:06:29 [Alarm CLEAR] Object 75 reason 28 Device FRU PEM 2, reason PEM 2 No Power(PEM 2 Not Powered), color 2, slot 0 Alarm id 1258299420

Jun 28 07:06:29 send: yellow alarm clear, device FRU PEM 2, reason PEM 2 Not Powered

Jun 28 07:06:41 PEM power status has changed, run power budget again

Power budget is power utilisation and consumption calculation associated with a system. It can be seen as net power balance of the system while in operation.  When Power budgeting is executed by the system and if an issue is detected on any PEM on the device, log message "PEM power status has changed, run power budget again" might be seen.
 

Power management manages power to router components by employing a power budget policy. In its power budget policy, power management:
 

• Budgets power for each installed router component that requires power. The amount that power management budgets for each component is the maximum power that component might consume under worst-case operating conditions. For example, for the fan tray, power management budgets the amount of power required to run the fans at their maximum speed setting, even if the current fan speed is much lower.
   

When PEM/Power supply fails or when a PSM is removed, power management :
 

• Calculates the total chassis power available from the remaining PSMs for the FPCs.
   

This log message indicates that power budget needs to be run as one of the PEM has indicated issue and power budgeting to the components needs to be re-run to assure all the components receive enough power to optimize functionality  else mitigative actions will be taken.
 

Troubleshooting the PEM issue makes the logs disappear on its own. Power management clears all alarms when sufficient power is available to meet normal operating and reserved power requirements.These logs are harmless in nature.