[j-nsp] MX960 PEMs and 3 phase power

[Tom Storey]

We have A+B power delivered 3 phase to the racks, broken out on PDUs, but I
think I must have been thinking about another platform in regards to not
splitting PSUs across phases.

Thanks!

On Thu, 23 Mar 2023, 09:15 Mark Tinka via juniper-nsp, <
juniper-nsp at puck.nether.net> wrote:

>
>
> On 3/23/23 10:29, Gert Doering wrote:
>
> > "typical" data centres over here have 2 primary feeds, either one
> > with UPS and one with generator, or both with (different) UPSes - but
> > depending on the load drawn by a rack, might be presented as multiple
> > circuits with 16A each, and individual circuit breakers.
>
> Same here, and also what we have seen at most of the larger data centres
> we work with.
>
>
> > Now, if another device next to your MX960 has a PSU failure and kicks
> > one of the circuit breakers, what do you want your MX960 to do...  as
> > well, what do you want to happen if the UPS fails, and one of the primary
> > feeds goes down.
>
> We typically deploy a full power complement in all our routers to
> protect against issues such as these, even when we may not necessarily
> need all that power Day 1.
>
>
> > We do not have MX960s, but we did have other devices with 3 PSUs that
> > needed 2 to fully power all line cards, and this was quite a bit annoying
> > - "it says redundant PSUs, but no full feed A / feed B resiliency"...
>
> Even with the 2nd generation high-capacity AC power supplies, the MX960
> requires at least 2 power supplies at a minimum, to power the 2 zones in
> the system.
>
> These power supplies have 2 receptacles per unit, to allow you to drive
> a full chassis running at speed with just 2 of them in the box.
> Otherwise, with just a single receptacle per power supply, you only get
> about half of the energy out of the power supply.
>
> Mark.
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