question

Hi Vincent. I'm up for a mystery.

The graphs look genuine, but I'm not sure why you suggest only resistive loads? Doesn't look like a microwave to me. If I tried to replicate it on my system I'd turn on a water hose outside, and the pressure pump (with an accumulator ball) would do just that. The size of the swing is much more than I could manage though, and might even be indicating a sick start/run capacitor on a small pump. Or it's big pump.

Just a wild guess, good luck tracking it down..

I'd start with connecting a laptop to the Quattro and looking at the values in real time. maybe the load is alternating?

btw through remote console you might also see enough data to get more info.

Thank you both for your answers. I'm at the location once in awhile, and I have walked past the inverters while they are doing this. I would guess its about every 10 seconds you can hear the relays clunk. Looking at the graphs, there are about 50 on/off cycles in 20 minutes so that's about right.

It's an office with about 20 computers running, a couple of data racks, 6 resistive base-board heaters, a small water heater, a small kitchenette, and a bunch of LED lighting. Oh there is a workbench with soldering irons and rework stations as well. So a bunch of random loads, none of which are motors.

I focus on the resistive loads because in the summertime the total load is under 1kW, and the winter we see up to 10kW sometimes... so the load profile is ~90% resistive heat.

I have complete remote access, so what exactly do I need to look at to analyze deeper?

And... does it even matter? The inverters are doing their job, I just want to "rest easy" that this isn't damaging to them, as it's a peculiar behavior I haven't noticed in other systems.

Clunking relays?? Before I say this I'll point out that I'm not especially familiar with the innards of a Quattro, and how it works..

It seems you're set up with fulltime 'grid' power and using it as ups. But a clunking suggests to me the ATS in the Quattro switching. If that's it, what's happening will be it rejecting the power supply and retrying constantly. Ie. the input power is being interrupted. My Multi shows no warning when this happens.

This is a common issue with generators, and documented here, along with a range of fixes, the higher level ones coming with efficiency and capacity penalties: https://www.victronenergy.com/live/multiplus_faq

I'm not aware of Powerassist cutting in with a clunk, But the ATS certainly does, and I'd suggest checking this out..

go into remote console - devices - multi - scroll down so you can see AC-in and AC-out (easy with a 1 phase system, 3 phase system doesn't fit in one screen.

here you can see realtime what the loads do, and how this interacts with the grid-input.

If you have UPS-setting enabled in the multi, it is very quick to unhook the grid when voltage drops, so when a load switches on, and grid drops, the inverter will take over and later try too hookup the grid again.

without UPS setting, it will be less nervous at grid fluctuations...but...how often do you have grid failures at the site? and will the computers / servers be affected by the bigger fluctuations?

When the grid is very unstable, you might also consider using a ' separate inverter to provide a stable feed to critical servers / PC's not influenced by grid fluctuations. (and with that might also safe equipment from lightning strike / other crazy stuff coming from the grid connection) this way you effectively create a double conversion UPS

NO sorry, I didn't mean to imply I was losing Grid or coming unsynced. It's not that clunk, its a different clunk (more like a click?), when it goes into assist mode.

As you can see from the logs I posted, its definitely cycling from Bulk to Power-assist, and spends no time in any other states between that.

The grid voltage is pretty stable during this event, considering.