basstscho avatar image
basstscho asked

UPS setup server room


i have a private ESS Setup (3x MP2 8kVA, Cerbo GX) together with some Pylontec US3000C. Everything works perfectly fine!

At work we have a smaller server room which needs new UPS. The total needed power amount is roughly 2x 1 kW (every equipment and server has 2 power supplies). Currently it is solved over multiple smaller UPS. The shutdown procedure and power survaillance is already idependant of the UPS. So the only need to provide power. The idea is now to build up a victron system: 2x MP2 3kVA, Cerbo GX, 2x Pylontec US3000C. This should increase the time significant, and it should reduce the amount of batterie changes.

Basically I would start to build a connected MP2-System with 2 (of 3) phases and the Cerbo GX to connect the BMS and the MP2-System. But since I don’t have experience with Backup-UPS setup of Victron, there are some questions coming up: The system should be as reliable as possible. So when one component fails, at least one MP2 should still provide power. Is this in connected mode the case, when one MP2 fails or are both shutting down? I also have read in the community, that may the switch-over time is faster in single mode. So since there is no technical need for me to have the MP2 connected in a system: Can a Cerbo also run with two individual MP2 in 1-phase mode? What happens when the Cerbo fails? Are the MP2 running in “fallback” mode without the Cerbo? Or do I better have to setup a complete redundant setup: 2x (1x MP2, 1x US 3000C, 1x Cerbo)?

Thank you and best,

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3 Answers
Alexandra avatar image
Alexandra answered ·


Both with shut down if programmed as one system.

You seem to have not totally decided what the system priority is here. Running two phases of supporting a small server room.

For total redundancy you would need an auto changeover and run the two systems individually with their own GX etc. Add more battery per inverter at least 2 if support for one phase.

If you are planning three phase in tell your supplier you are planning to do so, the units have to be same hardware version and age when you do add it. They should reserve a matching unit for you.

The other option is (if you do not need actuall three phase power for three phase appliances) is just have independent systems on each phase.

Look at the multi RS inverters (but you have to start with three for this and more battery) they can run with one unit missing/shut down in the system. The other issue is you will need more battery, so this is more of an all in now solution.

Victron are not certified UPS systems, the changeover is not always fast enough for the more sensitive equipment. Still have a UPS there even if it is a small one.

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Kevin Windrem avatar image
Kevin Windrem answered ·

Many UPS used in mission critical environments are the on-line type that have separate charger and inverter that run 24/7. The Multi is more like an off-line UPS and WITHOUT boost/buck.

You probably want two of a more traditional on-line UPS. Many are now available with lithium batteries and some are available with battery expansion.

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basstscho avatar image
basstscho answered ·

Thank you for the feedback. I don't need a 2 phase-system. 2x 1 phase works perfectly and therefore I will build it up with 2x Cerbo GX, 2x Pylontec & 2x MP2.
At max I need 2 kW: 2x 1kW and if one MP2 fails: 1x 2kW. So two batteries should be enough. Do you see a problem, when connecting the batteries at 48V, but every Cerbo is connected to one battery?

Cerbo 1 -> (BMS Can) -> Battery 1 <-> Battery 2 <- (BMS Can) <- Cerbo 2

Multiplus II 1 -> Battery 1 <-> Battery 2 <- Multiplus II 2

If for example Cerbo 1 and MPII 1 fails, the Battery 1 will be only "passive" connected with the System 2. Does this makes problems? Should the systen build up completely separate? In this case I would need 4 batteries.

We are currently running everything from some line-interactive UPS from Eaton. So it also has a small blackout time. When it doesn't run directly from the MP2, I will integrate again an existing Eaton UPS.

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Alexandra avatar image Alexandra ♦ commented ·

And if the central battery bank fails then two Victron systems are down. And removes the point of having a fail over system.

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