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Hi All,
My question relates to the Quattro with 2 AC inputs, during the transfer from one AC source to another (Grid to Generator) what is the interlock operation performed (mechanical or electrical or both) that prevents AC in 1 and AC in 2 from both being connected at the same time, even if it is very momentary? More specifically, during the change-over, is it a Break Before Make operation that prevents back-feeding of the generator to the grid if the grid has failed?
The Quattro will switch into inverter-mode for 20-30s before switching to the other AC input.
For example, with a Quattro 48/10000 and a 10kVa generator, a 16kW load will draw 8kW from the AC source (generator) and 8kW from the battery bank (inverter). While switching to input from the grid (other AC input) or vice versa, does this mean the Quattro draws 16kW from the batteries for 20s-30s?
The peak power is only for a few seconds for inrush currents.
It depends on various things (battery voltage, AC voltage, temperature, the kind of load ...). Sometimes it might work and sometimes not.
Found this...
https://community.victronenergy.com/questions/4454/peak-power-of-victron-inverters.html
200% for 0.5secs
150% for 5secs
130% for 30mins
This seems to be specified as current not power, so a 48/10000 (10kVA, 8kW long-term) should be able to provide 20kW/15kW/13kW for 0.5s/5s/30m -- so maybe 14kW or so for the 20s-30s switchover time?
Unless somebody knows better -- for example, a comment lower down said:
From my experience with different sizes of inverters (5, 10 and 15kVA) on the quattro range from both 120 and 230V ranges, I can confidently say and I have tested this several and enough times to say that the quattro range does not reach the peak power being twice the nominal power at all and any load just above the kVA P30 rating overload the inverter instantaneously. I am really interested to see test and real data from Victron proving that these inverters reach peak power.
Therefore, I do not recommend to design any system taking the peak power into account as you will end up with inverters overloaded, trust me.
Connect some non-critical loads to AC out 2 so they get switched off for that moment.
All I'm pointing out is that if you use Power Assist to power loads above the Quattro/generator/shoreline power rating by adding power sources together (a feature promoted by Victron), you might have a problem with overload while switching between shore and generator power or vice versa.
If you're saying "don't design a system like this", that looks very much like saying "you can't rely on Power Assist to always work how you think"... ;-)
AC Out 2 will automatically switch on again around 2 minutes after the new AC input is switched through.
PowerAssist is a feature that is only available as long as an AC input is connected and in use.
If you run a load with PowerAssist that is bigger then the Multi/Quattro can handle alone you will run into an overload if the AC input fails or is disconnected to switch to another AC input.
There is nothing you (or Victron) can do about it. Synchronizing to the input voltage and frequency takes some time, normally 20-30s but it can also take longer if the input is not stable(voltage and frequency is changing).
The normal use case is (in my opinion):
You are running on generator because the grid failed (and your batteries are almost empty). Knowing that you are running on generator you will not run all your loads at full power, only things that are necessary (and you batteries are getting charged).
If the grid comes back the Quattro can safely switch to inverter and synchronize to the grid without being overloaded.
You can also program AC Out2 that it only becomes active if the grid is available, not on generator. With that you can limit the AC loads running in inverter mode or on generator.
If you realy want to/have to run such high loads in inverter mode you should desigin the system bigger.
What happens if you want to switch to generator due to a grid failure and the generator fails to start in time or needs a few attempts to start? Also synchronizing to a generator can take longer than 30s. Quickly you end up with a few minutes until the Quattro can switch to the generator.
To avoid misunderstandings about what happens in cases like this, it might be helpful to write an application note describing what you just did (and the overload rating vs. time), because it's certainly not easy to find this out ;-)
Thanks for your prompt answer Matthias. Do you know where I can find some documentation on this? I may need to provide some supporting evidence to my electricity supplier proving that the AC inputs are in someway interlocked.
It have to disconnect the first AC input before it can start to synchronize to the other AC input and after that it can switch to the 2nd AC input.
If the transfer switch of the first AC input is stuck (for whatever reason) the Quattro is unable to synchronize to the 2nd input, so it can't switch on the transfer switch of the 2nd input.
I had been through the manuals prior to this community, I can find schematics of the contactors, but unfortunately no description on their operation. Perhaps I have missed it. I would describe it as having a software interlock given the syncronising and timing that is performed prior to the change-over, I need some information to provide the electricity distributor. I was hoping that it might also have electrical interlocking.
