Description

Customer got confused when receiving SRX5800 chassis with DC PEMs, but also seeing that AC inlets were available on the Power Distribution Unit:
PDU.jpg
 

Symptoms

Normally, the AC inlets on PDM should be covered like we see in the below image (there are multiple options available so it might look a bit different, but we should not use AC PDM if DC PEMs are used):
PDU_Covered.jpg
 

Solution

As we can see from documentation, we should not combine AC and DC PEMs as only the first type of PEM will be used:

"CAUTION:

The firewall cannot be powered from AC and DC power supplies simultaneously. The first type of power supply detected by the firewall when initially powered on determines the type of power supply allowed by the firewall. All installed power supplies of the other type are disabled by the firewall. If you install a power supply of the other type while the firewall is operating, the firewall disables the power supply and generates an alarm."

https://www.juniper.net/documentation/us/en/hardware/srx5800/topics/topic-map/srx5800-power-system.html#id-srx5800-services-gateway-power-system-overview
 

Modification History

2024-05-23 : Article Created