This article describes the scenario where an FPC shows "No power" under the output of "show chassis fpc"
The FPC is not showing any errors or alarms but is down indicating "No power"
The customer recently upgraded SCB2 to SCB3, which will increase the power consumption
All the PEMs are looking fine and there is remaining power available
Even when the PEMs are not at 100%, we need to confirm the zone which is powering the affected FPC is having enough power, on a DC power system, the FPCs from slots 2 through 5 are powered by PEMs 1 and 3, this is the zone1, we can see this zone only has 705 whats remaining which are insufficient for the FPC power requirements
PEM 1:
State: Online
DC input: OK (1 feed expected, 1 feed connected)
DC input: 48.0 V input (54500 mV)
Capacity: 2440 W (maximum 2440 W)
DC output: 594 W (zone 1, 11 A at 54 V, 24% of capacity)
PEM 3:
Capacity: 2240 W (maximum 2440 W)
DC output: 432 W (zone 1, 8 A at 54 V, 19% of capacity)
System:
Zone 0:
Allocated power: 1365 W (875 W remaining)
Actual usage: 810 W
Zone 1:
Allocated power: 1735 W (705 W remaining)
Actual usage: 1026 W
Total system capacity: 4680 W (maximum 4880 W)
Total remaining power: 1580 W
Furthermore we can see the PEMs are in a single feed setup.
The suggestions is to plan the power consumption based on the cards in used and if needed, provide more power to the chassis.
https://www.juniper.net/documentation/us/en/hardware/mx480/topics/topic-map/mx480-power-planning.html