Multi Unit XW Pro 6848 System Won't Qualify AC Generator

AlexDykes · August 2020

Hi all, this is my first post here so I'm hoping someone has seen this issue before. We have three Schneider Conext XW Pro inverters in a split phase parallel configuration. With an extended outage we finally decided to wire up the generator to AC2 and we can't get the inverters to qualify the AC input. All three inverters are connected as shown in the install diagrams with all three being connected to L1/L2/N to the generator, N and G are not tied at the generator as indicated in the manual. The voltage all looks right and the frequency is in range, all three show power on the AC2 line but never qualify the input. I'm not sure how much info is relevant to this so I'll info dump below. Anyone have any ideas? Could it be that the frequency is varying too rapidly? I've tried applying a small load to attempt to calm it down but that hasn't helped.

My current thoughts are: get a big Honda inverter generator for cleaner power, OR simply get a 48V generator with auto start and forget about the AC2 input.

They all share a 3000Ah Surette Rolls battery bank
We have the three inverters, two MPPT 80 600 chargers, the Conext gateway, SCP and battery monitor.
The inverters are set with the AC chargers disabled (although enabling made no differnce)
Generally the slave inverters are set to search mode, but we've disabled that and it makes no difference.
We've turned on/off gen support, adjusted the AC2 parameters, breaker size, etc
We've power cycled more than I care to admit.

Dave Angelini · August 2020

What faults or warnings are on gateway or SCP? You must enable the chargers as you know. You left out the genset you are using? Usually you need a neutral connection depending on the genset type. Who installed it please?

AlexDykes · August 2020

No faults or warnings on the SCP. We tried every permutation we know of with the settings. Charger enabled/disabled, etc. The generator is a Honda EM5000s which should be fine for our loads as we cut utilization drastically (1.2-2.0kW) when the battery is getting low. We installed the system ourselves, most of our neighbors are also off grid and we all use the same inverters and have a pooled knowledge base but we're the only ones running a paralleled configuration. The same generator is qualified on our neighbor's single XW 6848 in about 15 seconds, so it seems to be something with the multi-unit config. The neutral is connected as show in the Schneider docs.

Dave Angelini · August 2020

Schneider power distribution panel with multi unit lockouts, factory wiring correct? You should at least hear the gen set try and qualify, if not, as you said something is not wired correctly. That is about all I can say because I do not know your qualifications. Maybe someone else can help. Be careful with the grid connections in your panels. Good Luck

AlexDykes · August 2020

Correct, the factory PDP, etc and the factory wiring kits for the paralleled inverters. I'm an electrical engineer and have re-verified everything to make sure it's connected properly but unfortunately I don't have a scope handy to check how clean the power is from the generator. I'm assuming if the wave form is terrible and frequency is wandering too quickly the XWs will not qualify the input? Schneider doesn't seem to give detailed specs about exactly what parameters must be met within what window to qualify. We can adjust the voltage and frequency range, but if things are vacillating between say 55 and 65 Hz too rapidly, will it never qualify? That sort of detail seems to be missing.

mike95490 · August 2020

My older XW qualifies crummy power from 2 different generator/alternators
One is a recent vintage Subaru/robin/hatz 3kw diesel (which our gas oven's brain refuses to work with)
Other is 1930s 650 rpm diesel belted to a ST5 alternator head, which the garage door opener won't work with
AC2 input qualifies and tracks both, even the voltage flicker from the 650rpm diesel

MichaelK · August 2020

The default setting on the XW charger is 140A. Charging at 50+V >7000Watts. Your generator is rated for 5000W? That's why is isn't being qualified. It's trying to pull 7000W from a 5000W generator.

Go into the charger settings of the XW, and reduce the charging rate to a really low value like 10. Ten percent of 140A would be 14A, which at 50+V would only be a 700W load. The XW should easily qualify such a low load. Incrementally increase the charging rate every few seconds from 10 up to maybe 35. Thirty-five percent of 140amps would be ~ 50amps, or maybe around 2500W, about half-load for your generator. As you incrementally increase the charging value, you'll hear your generator being loaded more and more. At some point the generator will get loaded to the point that the XW will drop it again. That will be the "DO NOT EXCEED" setting for your XW.

I have no clue what your top value will be. I have an AC-Delco 6500W unit, and my XW lets me go up to ~37% before it drops the generator again. It will depend on the wavepattern of your generator, it's state of tune, and how warmed up it is. I would guess how long it's been since the last oil change also factors in?

Dave Angelini · August 2020

Yea but it is not even trying to qualify. You should hear the genset start loading and then cut-out, he says no! Certainly worth trying but something is not wired/configged right.

Also, XWP is 44hz to 70hz on AC2 max BTW.

MichaelK · August 2020

Dave Angelini said:

Yea but it is not even trying to qualify. You should hear the genset start loading and then cut-out, he says no! Certainly worth trying but something is not wired/configged right.

Well, yes, that's exactly what I'm talking about. As soon as I attempt to initiate the charger, the generator loads up for 1 second, then drops the load. It waits a minute, then trys again, and again drops the load, over and over. I think he should still try starting out with a very low load. One wiring detail I seem to remember somewhere in the XW installation guide is the presence of the neutral wire, which wouldn't seem important to me for a 240V charger circuit. I believe the manual states something along the lines of "the neutral is required for the proper referencing the 240V circuit". I don't really know what exactly that means, but when I made the wiring connection from my generator to the charging port, I used 3-wire cable (plus ground) to include the neutral. Following the procedure I mentioned above, that how I got my XW's charger function to work.

Dave Angelini · August 2020

It is not doing what you write according to the OP. Not even for 1 second.

No matter how the defaults are set, the AC2 input relay should energize and then disqualify if not set to reasonable settings. You should hear it. SCP and gateway should record this also.

Dave Angelini · August 2020

When he comes back he can clear it up. In the first post he said there was no neutral. Then he said there was.

I could also be reading in something that is not there. Would not be the first time

mike95490 · August 2020

I have neutral connected in my setup, and it works. I even use a EU2000 with an auto-transformer and charge from that.. Getting the EU2000 to accept a transformer, requires a good transformer.
( I ran my house for a week off the eu2000 & XW while I was refreshing my NiFe battery bank )

AlexDykes · August 2020

Neutral is connected from the generator to the inverter bank as specified in the documentation. What I said in the OP is that N and G are not tied together on the generator which the manual says is how it should be connected.

The inverters never try to pull power from AC2, it never gets to that stage. The XW's charger is set at the lowest charge rate, *BUT* I also have tried it with the chargers turned off and it makes no difference. If I take the same gen to my neighbor who has a single identical XW then AC2 qualifies in about 20-30 seconds. The only thing that I see different in the configs is that I am running a multi-unit config (3 XW Pros).

AlexDykes · August 2020

I can't help but think it has something to do with the multi-unit config. The real tell will be this afternoon because PG&E will finally have power restored. We usually operate in an off-grid configuration but I'll have mains power available and can connect the grid to AC2, that power is well within spec so I'll be able to see if it will ever qualify AC2 with it.

Dave Angelini · August 2020

OK, I have seen a few cases where the installer got into trouble and made a pretty basic config error.

Configuration is not just what you have programmed, but the circumstances the power system is exposed to.

When you are testing the genset, you are disconnecting the grid right?

You left out "together" in the OP BTW.

AlexDykes · August 2020

This is an off-grid system for all intents and purposes. We ran grid power to the inverter system as a "just in case" safety net but the power is disconnected 99.9% of the time.

AlexDykes · August 2020

The inverters certainly start to try to start the qualification process on AC2. When the system is inverting with no AC input, power out is right at 120V and 60 Hz. When we connect the generator, the inverters (all three) are seeing 119V / 63 Hz on each leg of the AC2 input and you can see that the inverter output of the XW paralleled configuration starts to match the AC frequency, it goes from 60Hz to the wandering ~62-63Hz that the generator is putting out.

Dave Angelini · August 2020

OK sounds better. Grid in is 0 v. So if you are starting to qual that is a different animal.

You hear the relay when you turn on the gen breaker after 20 seconds or so. You see the XW display change from power out to input amps?

I would enable the charger on the split phase primary inverter only. I would widen freq and voltage to max in AC settings. Make sure you are setting the breaker to 20A on AC 2. Limit the charge to 50%. See what you get.

The advice you get, at least from me is only as good as what you write. Not trying to be an ass either. Always good to go back and read it again. A nasty week here so I hope you stay cool. You have a good system, you should not need a genset if you are in a non coastal part of California.

AlexDykes · August 2020

No, the relay never engages, the system seems to be stuck in whatever phase comes before that in the process. The XW never tries to pull any current through the AC2 lines. This is monitoring via the USB tool or SCP (XW display doesn't change either). Gen input is certainly something we'll need long term as we are actually in coastal CA and in a redwood forest so there are times of the year where fog and cloud cover drop solar harvests by 80%

Dave Angelini · August 2020

Sounds like time to call it in.

When I tested the pro here for the field test, I did not run multiple inverters. Your idea of sending the grid into AC2 is a good one BTW.

Any way you could try this on the 2nd slave (unplug stacking) just to eliminate the master. Wire gen straight into AC2 in case something is not correct in PDP? Also, is firmware up to date? There were 2 new revs since I did the field test here. Borrow a Honda 7000i? That is what I spec for clients. Good Luck!

https://solar.schneider-electric.com/netsuite/

AlexDykes · August 2020

Firmware is up to date, Schneider suggested using the Hawaii firmware (HEICO) which is newer than the Rule 21 firmware due to some issue we had with the paralleled inverters at the initial install. I may try to go back to the Rule 21 firmware to see if there's a difference, I remember reading somewhere about a known issue when multi-unit configured but I can't for the life of me find it.

Dave Angelini · August 2020

Look in the firmware packet under release notes. Should help the brain fog. Also, when you test the gen, you should not have full batteries, probably not the problem since you do not hear the input relay switch, but keep that in mind.

AlexDykes · August 2020

Just a followup should anyone follow behind me. AC2 won't qualify with anything. Schneider says it is a known issue with the HEICO firmware but the Rule 21 firmware works fine. It only effects paralleled inverters, so solo inverters don't exhibit the same issue. We ended up on the HEICO firmware because its a newer release and it solved the erroneous anti-islanding islanding errors we were getting in the paralleled config but the trade-off is that you cannot use the AC2 inputs for anything at this time and AC1 won't do generator support of course. So we swapped the Rule 21 firmware in and are putting up with the anti-islanding errors until Schneider fixes the issue. I suspect we'll end up also going with a 48V DC generator that charges the battery bank directly which would be more efficient anyway.

Dave Angelini · August 2020

Thanks for the update! I have a multi unit going in next week. All I have installed is the rule 21 firmware but someone in Hawaii may need to know this.

Just a question of why you care about anti-islanding if you are off the grid 99.9 percent of the time in California.

If you use a DC genset it will not show power in on the gen input or your gateway screens. The efficiency gain is really a small amount as the Xw charger is power factor corrected.

Multi Unit XW Pro 6848 System Won't Qualify AC Generator

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