question

petajoule avatar image
petajoule asked

Failure of one Multi in 3p config - fast path to temporary restore?

Situation: 3p configuration of 3 Multiplus or Quattro devices.

Everything works fine, until it doesn't. Now one of them goes kaboom for internal reasons (i.e. device failure).

As soon as that happens, the whole system goes down "of course". Now the question is, how does one proceed to restore at least partial operation until the faulty device comes back from repair. Two phases could work which is better than 0 phases.

Assume the faulty device has been taken offline, and there are 2 - potentially working - devices left. until the faulty device is sent back, repaired and sent back-back it will take a week. What now?

Configure the remaining 2 Multis for parallel configuration is not going to cut it as they have different AC Outs - yes/no?

Simply turning off "switch as group" will also not cut it, because there still is one missing for a 3p config?

Reconfigure for 2p operation?

Is there a manual how to proceed for these cases?

3 phasesplit phasemulti phase
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nickdb avatar image nickdb ♦ commented ·

These are pretty much your options:

screenshot-2022-10-25-at-160953.png

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2 Answers
Paul B avatar image
Paul B answered ·

No options really as you have a three phase system so all 3 are needed to work.


if you converted everything to single phase then you could reconfigure them to be parallel - this is unlikley to be posiable as there will be generators and mains supply inward to consider.

or by pass the three multis completely so that the AC in and AC outs are joined on each unit and thus have them fully removed from the power system until you get that unit fixed.

Install a set of bypass contractors for each multi so that you can do the above if need be at a latter point in time with the flik of a switch.

Or if its super critical maybe buy a spare unit and keep the other repaired one as a spare incase it happens again.

Sorry I dont have any better news for you.


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petajoule avatar image petajoule commented ·
Not good enough.

Of course I have VE.Bus Quick Configure and VEConfigure at my disposal, of course I can temporary ditch 3p operation (see above 2p better than 0p).

So "all 3 needed to work" has no basis.

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Alexandra avatar image
Alexandra answered ·

@PetaJoule

No manual on how to proceed.

It is an installer /engineers / system designer decision.

Split phase setup with 120° out can work. If you still want to ESS.

Also on stand alone (one will have no gx on one unless you have one handy so no ess) will work and at this point you wont have three phase appliances working. Unless you always have grid connected in which case synchronisation is not a problem since it will use the grid for reference. Not recommend way though, but sometimes desperate times call for those kinds of measures.

As paulb mentioned if it is critical you would always have a spare on site anyway

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petajoule avatar image petajoule commented ·
I should probably have been more specific about this being an Off-Grid/no-ESS system.

Spares are ofc an (expensive) measure, but the question is about the principle what to do if you don't have a spare.

I mean - imagine a situation where you had a spare, you swap it in and 24h later it's gone too. Like bad luck, bathtub-curve, etc.

Unfortunately, Victron elegantly evades/ignores my queries about the MTTF specs for the devices, so whatever the MTTF for a Multi/Quattro may be, in a 3p config its 1/3 of that.


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nickdb avatar image nickdb ♦ petajoule commented ·

Failure mean times are an average (mean) across all devices that doesn’t change whether you have 1 or 10 devices. Statistically you may be more likely to experience a fault but a linear probability is just incorrect.

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