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UPS / ESS Solution

Currently working with a site that has a large CCTV network with a requirement for 5hr runtime off-grid should AC fail (very unlikely).


I am proposing to install a ESS consisting of single mulitplus inverter and bank of either Pylontec Batteries or Fogstar Energy Racks rather than a huge UPS without any room for expansion.


I need to ensure that no back-feed is possible, this system will only be used either to provide power during mains failure or to stay in standby and powering the load in bypass until required.


I understand that the Victron inverters do not operate in an "on-line" fashion as most conventional UPS's do so I figure the best way around this would be.


Servers connected to small UPS to provide "On-Line" UPS power along with graceful shutdown notification should the UPS battery run down if the Victron bank is used up.

This UPS would be connected to and served by the Victron system, we need 5hr max runtime on between 1-1.5kw load 230v (UK Based).


Can anyone sanity check my thoughts? I've seen a few posts here and there regarding floating earth and earthing arrangements in general.


The UPS that is currently in-situ is fed from a 16a 230v supply. There is room to upgrade this to 32a and above if needs be.


To summarise;


Currently

16a 230v -> UPS -> PDU in rack -> x3Servers / Networking equipment etc

--

Proposed

48v Battery Bank --V

16/32a 230v --------> Victron AC IN -> UPS for signalling to servers and safe shutdown -> Servers Fed from PDU


ESS
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matt1309 avatar image matt1309 commented ·

Hi @threatspot


Going the victron route is one expensive UPS however if it's commercial then maybe it's worthwhile. I'm not sure how Victron switching speeds to compare to UPS so better to keep them in just in case like you planned if the systems are critical for that reason along.

However with node red built into gx device on venus os large you could more than likely trigger shutdown directly from victron rather than via UPS.

Or even just adding a python script to read dbus directly. (Overkill node red would be fine)

In terms of earthing arrangements it will depend on what's currently used for earthing on the room at the moment. Given you're essentially setting up islanding mode for when grid goes down. The easiest solution in my opinion is if you have earth rods/TT system, however probably worth getting a spark in just to check whatever earthing arrangement you go with (only a concern when grid goes down).


Sounds like a fun project though!!


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mvas answered ·

What do you mean by "on-line" mode ?

I understand that the Victron inverters do not operate in an on-line fashion as most conventional UPS do so I figure the best way around this would be.

By "on-line" mode, are you referring to the "Online Double Conversion" mode per an APC UPS?
No, most conventional APC UPS do not have "Online Double Conversion" mode
Only the high end UPS models use "Online Double Conversion" mode.
Conventional UPS - switch from "straight thru" mode, to battery + inverter mode, via a relay.
Victron does a very similar thing.
The AC output from the Victron should be clean enough, to keep the original UPS functioning.
You will need to test and verify the above statement is true.

You should not be changing any "earthing" ...

I have seen a few posts here and there regarding floating earth and earthing arrangements in general.

Is this a question?

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threatspot avatar image threatspot commented ·
Yes I meant double conversion, I was planning to keep the existing UPS to take advantage of its low transfer time vs the Victrons 16+msec.

Thanks for the help!

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