I have a nice system on a boat with two multiplus2 5kva (not the 2x120). My 50a split phase Shorepower runs through the inverters before going to The AC panel where it feeds two separate 120 volt sections and a 240 volt section.
I typically run “switch as group” off in any mobile application and it works as expected but one thing I find annoying is that sometimes the system will reject L2 and it still works but it only pulls current from shore L1 and the second inverter makes the L2.
This is fine in fact it’s excellent functionality in case I want to plug into single phase 30 amp or etc. Except the problem is if we’re at the dock and we have very heavy consumption like when all air conditioners are cranking and we’re cooking and water heater going etc. there are times when I overload the second multiplus which is inverting.
The thing that’s annoying is that I can’t see anywhere in the Victron ecosystem what the incoming line to line voltage is or why we have rejected the L2 shore power. Most likely it’s because the marina has a 208 volt transformer and maybe I’m only getting 200 volts at the end of a long dock with heavy usage.
Two things:
I would like to have the data so I can make a decision about possibly turning off switch as a group.
I would like to know what the threshold is where the system will reject the second phase.
If the shore power was 220 volts and switch as a group is saying reject I might elect to just use the 220 v. If it’s 200 volts I probably wouldn’t. But I can’t see what the voltage is unless I get out my multimeter and probe it myself or if I turn off switch as a group and let it transfer through to my AC panel I have a meter there and I can see it then.
Am I missing something that would help me with this? Is there any documentation about how US split phase is evaluated and accepted or rejected by VE.Bus?
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
2
You’re probably seeing 208V because the marina has three-phase power and the 50A outlet provides two legs of 120V (L-N) and 208V (L-L) at 120° phase rotation. If the equipment in your boat can handle 208V vs 240V (it likely can), then what you need to do is set up your VE.Bus system to dual-phase 180° like you have right now, but also set the L2 to be floating with return to phase. This will allow both inverters to synchronize at 120° and 180° phase rotation. Try that and see it solves your problem.
yes I agree and understand what is likely happening. I fully understand how marinas often use 3-phase power. The problem is that 208v quickly becomes 200v or even less when the dock is filled with boats pumping air cond on a Holiday week (or just because it is a long run and etc.)
I understand I can turn on switch as group and let the L2 float but I don’t have the information to make a good decision. If I am getting a full 208v maybe my 240v air conditioners will be fine. But if I am getting 200v I am thinking twice about it. I’m not interested in burning up the windings in my compressors.
What I wish I had is:
I would like to have the data so I can make a decision about possibly turning off switch as a group. I wish I could see in Cerbo/VRM what the line to line voltage is coming in.
I would like to know what the threshold is where the system will reject the second phase. Does VE.Bus allow 208v 120deg phase rotation? Does it only reject if voltage is below…what? 205v? Who knows? Or does it reject true/full/normal 208v? There are no settings for ranges of line to line voltage ranges like there are for each single phase which you can set yourself.
Sure enough. Decided to turn on “switch as group” and now I can see that line to line voltage is way low. It was even lower at 197v before I got my photo.
I’m aware of these details and all the settings necessary to either pass through the power that’s arriving or to have my system make the L2 itself. The question is: am I missing somewhere in the Victron system to be able to see the data about line to line voltage.
I would like to be able to make an informed decision before going through the hassle of setting up VE.configure to adjust the settings each time I arrive at a different Marina.
It just seems very un victron-like to not be able to see some of this most basic primary data about the function of a very common US split phase system.
