When multiple PEMS are used to power the device, sometimes the DC output shows 0w.
user@srx> show chassis power detail node 1
node1:
--------------------------------------------------------------------------
PEM 0:
State: Online
AC input: OK (1 feed expected, 1 feed connected)
Capacity: 2050 W (maximum 2050 W)
DC output: 0 W (zone 0, 0 A at 57 V, 0% of capacity)
PEM 1:
PEM 2:
PEM 3:
DC output: 1829 W (zone 0, 31 A at 59 V, 89% of capacity)
This is an expected behaviour when the actual power usage is less than the maximum capacity of the one PEM.
Although the load is shared, this may be due to the fact that the other PEMS that show 0w were replaced/failed to work when the device was powered ON.
For example:
System:
Zone 0:
Capacity: 4100 W (maximum 4100 W)
Allocated power: 2822 W (1278 W remaining)
Actual usage: 1829 W
Total system capacity: 4100 W (maximum 4100 W)
Total remaining power: 1278 W
As we can see above, a total of 4 Power Entry Modules (PEMs) are installed on the SRX, each with a capacity of 2050W.
The combined power capacity of all 4 PEMs is 8200W (4 x 2050W).
However, the current power consumption is only 1829W, as shown in the output.
And we still have an extra 1278w of power which is supplied by the same PEM. Hence, the load is not shared in this case.
To reset this behaviour, we will need to either reboot the device or re-seat the active PEM (PEM3) in this case.
This will force the chassis to share the load among existing PEMs.
The chassis is getting all the power required from PEM3. PEM3 is not yet aware or programmed to share the load as soon as the PEMs are added.