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sa-victron-user asked

Does the Victron system perform full UPS function?

I am new to this and my system was only commissioned at my holiday house a few weeks ago. My setup currently runs on solar all day (unless the weather is bad) and battery all night (unless the battery drops below 40%) other than 300 watts per hour of grid power. If the gird fails, my circuits which are designated as critical loads will run from the battery and 40% of the battery will give them around 8 hours. It appears to me (based on a few weeks of monitoring) that the system will be on “grid only“ power for about 10% of the time (presumably more in winter) and probably increasing to about 60% of the time when we are actually using the holiday home.

My understanding (and I may be wrong!) is that the system will protect from poor quality power (surges, high voltage etc.) from the grid when the battery is in use and when the solar is in use but not when the power consumed is “grid only”. Assuming this is correct, is there any way to protect the critical loads from dirty power all the time using the system or does one need a separate stand alone UPS?

Thanks in advance from a real newbie!


MultiPlus Quattro Inverter Chargerups
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4 Answers
JohnC avatar image
JohnC answered ·

Hi @ SA Victron User.

Presumably you're using a Multi or Quattro with the grid input passing-through to the loads. In this setup dirty power is certainly rejected if need be, and often impinges those with crappy generators.

The blue boxes in default mode are very particular about this, but can be 'relaxed' if you choose.

They can work as a fully-functional and safe UPS, or with custom modifications as you've applied.

There's no need for an additional UPS. Your power will be clean..


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kai avatar image
kai answered ·

I largely agree with John, I wanted to highlight a particular point which is that the Victron converter platforms do have a non-zero transfer time, if say the grid goes out and it goes from pass through to inverter operation. For most modern equipment, the delay won't be noticed. If you have a particularly critical load that absolutely has to remain uninterrupted during such an event, please test it first to ensure it would do so.

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sa-victron-user answered ·

@kai and @JohnC - thank you both for your answers. This really helps. I have 3 of the blue Quattro boxes (48/10000/140) and a Fronius PV Inverter and a Freedom Won 40kwh battery.

I have tested that when I drop mains, the critical systems stay up (as my installer warned me that there was a very short (non-zero) drop. My installer has done a very good job of setting this up but made the comment that the system will not provide UPS type protection (from dirty power) when the power is not going through the inverter due to it not using the battery or solar at a given time (e.g. When there is not sun and the battery has reached its preset lowest state of charge. Hence my concern, but it sounds like I have nothing to worry about! Thank you!

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

You have several settings to define how good/bad the grid must be/is allowed to be to get accepted/rejected.

This are the default settings for a 230V device.

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kai avatar image kai ♦ commented ·

Certain UPS types will "clean up" the AC as power flows through the UPS (e.g. double conversion and ferroresonant topologies). The quattros won't do that because they pass the power straight through. However as M. Lange and JohnC mentioned, the quattro can be configured to switch over to inverter if certain (configurable) conditions are met.

For most users this is as good as a "clean up" UPS; the cost of course is needing to draw power from a non-grid source. The scenario that your installer described is a worst case scenario where the system has used up its battery reserve, coinciding with a grid brown/black out. In that particular case, no, the quattro won't "clean up" the AC in. But you should have plenty of warning time before it gets to that point to do something about it.

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JohnC avatar image JohnC ♦ commented ·

Yeh, this must be a substantial 'holiday house', and with 30kW of Quattro, ac-coupling, etc., a little beyond what my initial answer (conditional) was attempting to address. But what you've passed on that your installer has told you seems fine. I'd trust him.

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

Is this perchance an install on the north coast of KZN?

The advice about the dirty power was given because of this:

  • When the Quattros are producing AC from solar or battery, they are converting DC to AC and have full control of the resulting quality of that power. The same applies for the power being produced by the Fronius.
  • However, when there is no solar and no battery; then all the AC being supplied is coming from the grid and there is no DC to AC available for smoothing.
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Henrik answered ·

Maybe for clarification please note that there are three classes of UPS systems on the market:

- the simplest UPS type - bridges power losses within less then 20ms without any input voltage corrections etc. Sufficient for most consumers, but sometimes not sufficient or sensitive IT server equipment. (--> Thats what the Victron inverter UPS function does)

- line interactive UPS: Do the same as above but correct the input voltages up or down if too low or too high (--> many cheaper UPS systems work like this)

- online double conversion UPS: Best type. These UPS create 24/7 their own super stable power output out of the built-in battery. The input power is never passed through, it is just going into the batteries for charging. Out of these the UPS forms a completely independent new output power. These UPS are highly recommended for IT server UPS applications and sensitive equipment.

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soren-dynamicmill avatar image soren-dynamicmill commented ·
Hi, im trying to do the "the simplest UPS type" with Multiplus 48/1200/13 but don't get the transfer time of 10ms its more like 10s. And I cant understand why it takes a pause when going from Grid loss to UPS/battery. It takes a long time before the inverter kicks in.
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energy avatar image energy commented ·

Thanks for that Hendrik. In South Africa with Eskom not complying to NRS-097 a double conversion UPS is the only option for sensitive equipment, like my son's R1.5M sonar scanner. All the Bla-Bla-Bla responses talks about a 20ms switch to inverter function. So what?, any cheap chinese inverter does that.

I am not aware of a setup that utilizes the Multi-2 as a double conversion UPS, although the hardware functional blocks are all there. Am I missing something in the setup options, OR, is the only option to configure a DC coupled charger and inverter?

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Kevin Windrem avatar image Kevin Windrem energy commented ·

All Victron inverter/chargers use a common "core" to either charge the battery from AC input or to supply AC loads from the battery. When the AC input is within acceptable range (voltage and frequency), the core is synchronized to the AC and the AC input is connected to the AC output. Any variations in incoming AC are passed through to the AC output. While the input is connected, the core will either charge the battery or "assist" in providing load power if the incoming AC is not sufficient.

What you need for a double conversion UPS is to separate the charge and inverter functions. You can do this with two Multiplus (or Quattro) inverter/chargers, one connected to the AC input and one connected to the AC output with a common battery bank in between.

Victron also makes separate chargers and inverters that may be less expensive. One advantage to this approach is that many of the carriers accept a wide range of input voltages. For a mobile installation and sees 230 volt 50 Hz and 120 volt 60 Hz shore power, the charger will adapt to the incoming power and the inverter will produce stable power at voltage and frequency expected by the loads.

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