Schneider Conext XW and GenSupp Plus

Re: Schneider Conext XW and GenSupp Plus

I have measured the loaded power consumption of the PSX-240 at less than 12 watts with a 2 kVA imbalance and ~55 watts @ 4.5 kVA. So the insertion loss for the PSX-240 is very, very low with loads balanced within a couple kW. The transformer will actually handle 60 amps on a balanced load. It's 6 kVA rating is what it will handle for imbalance. If you examine the windings of a PSX-240 they appear to be 10 AWG and the resistance of the primary and secondary is very low.

The transformer in the XW is the same deal - the I^2R loss in the windings will depend on the design, so it's not "free". So I now understand why Mike Mui (Schneider Tech Support) recommended to me to install the PSX-240 on the output of our generator - using it to balance the generator is more efficient than using the XW's internal transformer, and we get perfect generator balance during charging with the PSX-240 as well. Schneider was concerned about our small generator being disqualified by the XW during battery charging with a large leg imbalance issue because it can only supply 20.8 amps on either leg for 15 seconds and 15 amps continuous.

For this test I measured the imbalance (or lack thereof) on the output of the PSX-240. During charging and normal operation I see imbalances on the legs on the PSX-240. But with GenSupp Plus enabled, and using Gen Support mode, the XW can balance your generator.

Now, it says in the manual to not use a larger than 5 kW generator for Gen Support, and once you understand it, the reason for this is obvious. If you look at the wiring of an auto-transformer it is like a see-saw. With equal weight on each end of the see-saw (no leg imbalance) you are powering up the primary (or secondary) at 120+ on the sine wave and the other side at 120- simultaneously. And the see-saw is rocking back and forth 60 times per second. Nothing happens as long as the loads are balanced - there is no current flowing in the windings and the only losses is in switching the polarity of the core @ 60 Hz.

As soon as you introduce an imbalance, current starts to flow in the windings and neutral, and the transformer does what auto-transformers do - the flux density on the heavier loaded side is higher and it assists the input on the other side of the transformer. There's a limit to how much one side of the transformer can assist the other side, and that limit is 5 kVA in the XW's transformer. Once you exceed that you get a circulating current between the legs and a loss in efficiency.

I'm one of those weirdos that has to know how things work or it bothers me and I can't sleep at night. I'm satisfied that the XW is a solid unit and about the only way you could hurt one is to run over it with a bulldozer.
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Chris

Re: Schneider Conext XW and GenSupp Plus

NorthGuy wrote: »

How are you going to charge the batteris? You probably need at least 15A for this. That's 7.5A on L1 and 7.5A on L2. Any time a single-legged 8+A load comes in, the leg will hit 15A, it'll be dropping charging and start supporting.

No, 15A is 15A RMS on each leg. That amps setting is at 240V. It charges batteries just fine and as loads increase it dials the charger power back accordingly until the gen overloads - and then it supports the gen.

Unless you change the jumpers inside for 120V output and change the firmware for it, all settings in your XW are for 240V, not 120V.

On the Home Screen where it display watts, that's total watts of both legs combined, regardless of imbalance. But the menu settings are for 240V, and split phase power is L1 -> L2 with imbalance current flowing in the neutral.

I haven't done enough testing to determine if the XW calculates amps including imbalance (sum of L1 and L2 divided by two) or excluding imbalance (real time peak on either leg).
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Chris

Re: Schneider Conext XW and GenSupp Plus

NorthGuy wrote: »

I found that mine does it differently. I don't know about GenSupport but the AC2 Breaker operates on the highest of L1 and L2 currents, not on average. As the highest of two starts hitting the limit, it starts to dial back. Charging is, however, always equal on both legs. For example, if you would have 15A limit, and it's a 10A load on one leg, you get only 5A charging (5A on one leg and 5A on the other leg). so that overall [load+charging] becomes 15A on one leg and 5A on the other. At least that is how mine is doing this.

May be I have an obsolete firmware. What's your firmware version?

We have 1.07 firmware.

Ours does the same thing as you describe with charging, which I would consider completely normal for a split phase inverter. Like I said, I haven't tested it enough to know if it's using the peak of either leg or the average because we haven't run it much out of balance when I've been watching it. I have to put my clamp-on meters on it to know what it's doing, and the first time I did that I tested that GenSupp Plus to see what it does, and was quite pleased to see that it works.

What I got confused over is when you said:
You probably need at least 15A for this. That's 7.5A on L1 and 7.5A on L2.

Ours definitely does not work that way. 15 amps is 15 amps on BOTH legs, not 7.5 on L1 and 7.5 on L2. I'm going to do some fiddling with it tomorrow when I get some time with some imbalances and figure out if it uses the high leg for determining generator load. I'm pretty sure, like you say, that it has to because it would take some wizardry in there to do it any other way. I think with our auto-transformer on the generator we got considerable leeway because I am able to use the full output (overload) rating of the generator for the AC Breaker size without actually overloading the generator - AND I got the inverter set to start Gen Support before that happens.

I dunno - it works so seamlessly here that I'd have to deliberately screw something up to invent a glitch in it.
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Chris

Re: Schneider Conext XW and GenSupp Plus

NorthGuy wrote: »

I probably misunderstood you. I thought your generator was 30A 120V (probably because you used it in your 120V before). And you use PSX-240 to convert 120V to 240V.

Ah, yes OK. That's what we did originally. That was what Mike at Schneider recommended. I was the one that got the wild hair to put the generator on 240V output (it will do either full power 120 or 240) and use the transformer on the inverter output to balance everything. That didn't work because the generator could not carry the loads by itself on leg at only 15 amps.

So I put the transformer back on the generator. But also like I said before, our Honda is a not-normal generator from the standpoint that it's what any other manufacturer would call a 4,000 watt generator. You pull the others down to 5,000 watts (125% of "rated" output) and they'll fall flat on their face. The Honda don't. It's computer-controlled engine and generator will deliver 125% of "rated" for a full 15 seconds and maintain 120/240 and 60 Hz - and then the worst thing that happens if you leave it at that load level is that the voltage starts to drop very gradually to where after about 5 minutes at that load the voltage will drop to about 112/224 but the freq is still at 60 Hz. Due to the voltage drop as the stator windings heat up under overload the actual output ends up being about 4.7 kVA after five minutes.

There are very, very, very few generators that can do that. Usually that sort of overload capability is only found in commercial/industrial grade prime power generators. Honda, a company that prides itself on not being outdone in the engineering dept no matter what it takes, put it in a portable, for pete's sake.
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Chris

Re: Schneider Conext XW and GenSupp Plus

I haven't studied the manual or read about what it takes to upgrade the firmware in a XW. But I think it would be easy to do should it become necessary. Someplace I read about a XW config tool (I'd have to read more about it at this point) so it's probably not a lot different than upgrading the firmware in my Classic 150's.
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Chris

Re: Schneider Conext XW and GenSupp Plus

NorthGuy wrote: »

XW Config tool doesn't come cheap.

No, but we bought our inverter from a brick and mortar local dealer, even thought it cost more than buying it online. The dealer has one of those things and if I need to use it they'll let me use it because I've done business with them for years.
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Chris

Re: Schneider Conext XW and GenSupp Plus

mike95490 wrote: »

(they only email it out, no FTP site to pull it from) and you have to start over.

Actually, when I have requested tech information or a manual download from Schneider they have always sent me an email with a link where I can download the requested information. The link is usually good for like 24 hours, or whatever.

Your description is about what I figured - it's a pretty simple process. Really no different than upgrading the firmware in a Classic controller, except different tools required.
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Chris

Re: Schneider Conext XW and GenSupp Plus

Mainly for NorthGuy,

I have played with our Outback PSX-240 on the output of the generator, allowing the inverter to handle leg imbalances but keeping the generator balanced. And also on the output of the inverter, which leg balances BOTH the inverter and generator simultaneously. After switching it back and forth a couple times to test things, it is better on the output of the inverter. I got the transformer wired in to the main disconnect panel for the inverter with #8 Type SEOW cable (easier to bend around sharp corners), and the transformer is using the 240V from the inverter to power the 120V loads (we have separate panels for 120V and 240V being we used to have a 120V inverter).

Attachment not found.

The main advantage with using the auto transformer on the inverter output is that the inverter runs more efficient and has more capacity before it calls for the generator with Load Start. One of the side effects is that you get more power from the charger with the transformer on it. If you have a leg imbalance the XW will use the value from the highest loaded leg to de-rate the charger, leaving the other leg basically idling. With the legs balanced you get your full 80% of the AC2 Breaker setting, minus de-rate for loads, at all times.
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Chris

Re: Schneider Conext XW and GenSupp Plus

Yes, it does a beautiful job of balancing the inverter AND generator. I think the inverter runs more efficient when it's leg balanced and whatever losses there are in the transformer (which is very, very low) is made up for in increased inverter efficiency, so it's a wash.

The only caveat is that you need to split out your 120V loads from your service panel and put them in a sub panel. For us this was no big deal because 120V is all we had for years, other than the well pump on a transformer. When we put in lots of 240V stuff here we put in a new 240V panel for it. I know from putting in generator transfer switches that when you remove 120V circuits from a service entrance panel that the wires don't always reach to put them into a sub panel. So it can be a pain.

I believe that for most people it wouldn't be necessary to leg balance the XW. But if you want to push the inverter and charger to its raw limits the transformer makes a world of difference.
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Chris

Re: Schneider Conext XW and GenSupp Plus

Bill, the transformer, going from split phase to split phase does not do a perfect job of balancing - just like the XW's internal transformer in GenSupp Plus where it hooks the transformer center tap to the AC2 neutral. It balances some, but not perfect.

If you feed it split phase and pull 120V off it (step down mode), then it balances the inverter legs almost perfectly. With the transformer in step down configuration feeding the 120V loads, and the split phase loads coming direct off the AC disconnect panel for the inverter, it stays within a 1/2 amp between the two legs on both the inverter and the generator.

Frankly, I think the auto transformer is a better option for leg balancing the inverter to get the most out of it at the highest efficiency than converting it to 120V and changing the firmware for it.

Like I said, for most people who don't push it to the limits it's not going to be a big deal. But if you push the XW to its limits, both in inverting and charging, as well as your generator, the auto transformer works. With #8 wire into and out of the auto transformer you can feed it 25 amps split phase and get 50 amps surge and 40 amps continuous @ 120V out of it. If you got more than 40 amps of continuous and simultaneous 120V loads you should be looking at converting some things to 240V in your house, is my opinion. So the PSX-240 is sized about right for the XW6048 to use its full rated output on 120V loads (if you have to).

You can get #6 wire into and out of the PSX-240. But it's a bear because #6 THHN is hard to bend around corners, and there's a limited amount of room in the PSX-240's wiring raceway. So a 40 amp 120V panel works out good with #8 wire feeding it, and is fairly easy to wire up.
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Chris