Installation on a musician’s tour bus. Split phase Quattro 24/5000/120’s. Bus has 50A, 240V generator, and 50A, 240V shore connection. Weird issue where shore connection -sometimes- doesn’t work. More details below.
System was originally installed several years ago (by someone else) and worked for years with no issue. Then one of the Quattro’s failed (unclear why). I replaced both Quattro’s with new units, installed exactly as before (same wiring, etc). And tried to make sure they were configured exactly as before (I could only see the settings on the ‘still working’ Quattro, but I copied/saved those and used for reference when setting up new units.
The bus has a ‘home’ location with shore power available. When at ‘home’, the system works exactly as expected. Shore power works, generators works, everything looks great. But when it goes out on the road, and they connect to shore power - the shore power doesn’t work! It shows as ‘disconnected’… BUT looking at the CCGX display, we can see that AC IN 1 and AC IN 2 have ‘good’ (I.e. 125V/60Hz) power. But 0 Amps/Watts - the Quattro’s won’t actually use the shore power. They will use the (SLA) batteries and invert, but won’t pull from Shore. Firing up the generator works fine, but… shore power doesn’t work.
This has happened at multiple locations, and happens at locations where the -old- system worked fine, so… doesn’t seem to be a matter of poor quality power. In any case, system is set to ‘accept wide AC input frequency’, with the default limits on upper/lower voltages. Again, though, the values being reported on the CCGX (at AC IN) seem ‘good’.
For the record - there are no ‘assistants’ set up, and the generator is not set up to auto-start. It is just manually started when needed.
Perhaps the shore power at those locations isn’t truly split-phase, but just the same 120V on both legs? Meaning 240V isn’t actually available those locations.
There is a mode for the second quattro when you configure it called Split-phase (180 Automatic) or (floating) that can be used in this situation that might help.
Thanks Rick - I can try that. If the shore at these locations is not actually split phase though, wouldn’t the bus have been unable to run 240V loads (previously, with old setup)? From what I’ve read, the ‘float’ is only +/- 60deg, so it’s not possible to take two ‘in phase’ 120V legs and turn them in to split phase.
On this note though - maybe these locations -are- split, but are not truly 180 deg out of phase, so using the ‘floating’ setting could help compensate for that?
You are correct, 240V loads would not have worked, so maybe that isn’t the issue.
It is really hard to find documentation on the (floating), now called (180 Automatic) configuration setting anywhere in Victron’s documentation. At least I haven’t seen anything.
Googling it provides opinions and descriptions, but nothing in an official manual.
If you find anything official, please let us know, thanks.
It is not uncommon to find two legs of 3-phase power feeding 120/240 volt receptacles. This typically isn’t an issue in an RV because there are no 240 volt loads. However any 240 volt loads will only receive 208 volts when running on shore power in this scenario.
“Floating” does not support in phase but will work with two legs of 120/208 3-phase power.
The only real way to address this would be to have a transformer at the shore power connection to take 120, 240 or 208 from the source and convert it to 120/240 split phase that’s truly 180 degrees apart. This would need to be an isolation transformer since you need to create a fresh neutral. The input winding would need multiple taps for 120, 208 and 240 volts.
Thanks Kevin. This bus really does have 240V loads (Air Conditioners) but I suppose they may work with 208 power, or at least no one has ever noticed an issue before. Will give this a try, at least.
I agree with the above, I’ve ran into similar installations where parks have double tapped a single phase to feed both legs of a 50a receptacle. Yea it works for 99% of RVs as the split phase 240 isn’t used, but the 1% out there are going to have grief!
Would you happen to know of anyone who makes such an isolation transformer? My google-fu is not strong on this topic. I did find an almost solution from Foster Transformer Company, but their product line stops at 5 kVA which isn’t enough.
I think it would do all you need: 120, 208, 240 volt in, 120/240 split phase out.
Another way to accomplish this is to use a second transfer for a “trim voltage” wired in series with the main primary winding. To bring 208 up to 240 volts you’d need a transformer with a 240 volt primary and about a 36 volt secondary.
Thank you very much. Showing my ignorance This lists 208 and 240 on the primary. I’m afraid it’s not obvious to me how to also supply 120 on the primary. I’m headed to the refence stacks to figure out how to make that work.
Following back up on this - it turns out the 240V loads on this bus were solely for resistive floor heaters. Setting the split phase configuration to ‘Floating with return’ solved the issue. Client put meter to a few hookups and sure enough, was seeing 208V, indicative of 3 phase power. Since they don’t really truly need 240V, no need for transformer.
Thank you very much. I should have read the data sheet versus just the marketing overview. I’m working through the connection diagram. Thanks again for your time.