I have an MX240 with two PEMs, located at PEM0 and PEM1:
Is it the correct location if I need redundancy?
For AC power supplies if your power source is 110v then you need two supplies for basic operation and they would be in slots 0 & 1 as you have them. In this case there is no redundancy. You would need 4 power supplies for that and install in all 4 slots.
If you have 220v feeds for the power supplies you can have redundancy with just two power suppliies and they would be installed in slots 0 and 2.
Thanks, but we have the power supplies in PEM0 and PEM1 and a short time ago a power broke down and the chassis continued working correctly which leads us to think that we have electrical redundancy. Our power supplies part number is 740-022697, is it possible?
For full dual feed redundancy you need to have power supplies in at least 0 and 2.
What matters for AC power supplies is the feed size. For AC supplies you may need all 4 if the power feeds are 110v and not 220v.
All the details are here.
Thanks for your reply.
Our AC power supplies are 220v. When we use "show chassis hardware" command we can see PS 1.2-1.7kW; 100-240V AC in and when we use "show chassis power" command we can see Capacity: 1590 W (maximum 1590 W).
Also, our AC power supplies are in PEM0 and PEM1 and according to the documentation that you have give us, for redundancy, the AC power supplies should be in PEM0 and PEM2 so, if we keep them in PEM0 and PEM1 and fail the PEM0 we will not have redundancy?
Juniper AC power supplies are what is called universal supplies. They work if they are connected to either 110 or 220 feeds.
The question is for the electrical panel input feed to the power supply. Is the eletrical feed sending 110 or 220 volts to the power supply?
If you are connected to 220 volt feeds then you install in pem 0 and pem 2 for full redundancy.
If you are connected to 110 volt feeds you need 4 power supplies for full redundancy and use all 4 slots. If you only have two 110 feeds you need to use both pem 0 pem1 for full power to both power zones of the mx240.
Is there any way to watch the feed using commands?
Not that I have found. The detail command does show the feed voltage for DC supplies but I could not find a command to show the voltage input value on the ac supplies.
You will need to check with the facilities group at the site to see if the circuits are 110 or 220.
Thank you very much.
Power Calculator Beta version is good tool to get some rough value of the box load w.r.t power