Balancing the Loads of my Conext SW with an Autotransformer

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  • mcgivormcgivor Posts: 2,203Solar Expert ✭✭✭✭✭
    Good to hear, questions are always welcome, just trying to offer other solutions.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 16 #33
    mcgivor said:
    Good to hear, questions are always welcome, just trying to offer other solutions.
    Thanks.  And I do appreciate it.  I had seriously considered the other option,  but when the parts offer fell thru, and I found the PSX for 1/2 price seemed like a good idea at the time.    It also seems easy enough to wire up.   So I am hoping this will be a good fix for the SW inverter and it's AC Support Mode in North America.  (obviously, markets where 120v service is not use,  load balancing is not a problem for the SW)
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    Someone just responded this to me on the Outback Power forum.    It might be that he is correct ...

    I don't know the SW topology but from your description, it sounds like the SW has an internal transformer creating the split 120/240 output. If this is the case I don't think you will have much luck balancing the load with an auto-former (PSX-240 etc). Your best bet would be to balance the loads/circuits in your AC panel if possible. It works for the OB FX inverters because they are two isolated power supplies that are set up to work as a 2 wire 240V circuit. The auto-former is the only point of inductance between the two.

    But if this is true,  why would the PSX work to balance  the power coming off a generator?   The PSX is also used in that application.  (pardon my ignorance,  this is an honest question,  not a challenge.)
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mcgivormcgivor Posts: 2,203Solar Expert ✭✭✭✭✭
    In the Outback example, both neutrals are common, so in essence it's the same as the SW, wether the source is two inverters or a transformer providing a split phase, as long as there are two live and a single neutral what would change?  This is logical thinking of course, sometimes things need to sink in to come up with a rationale why it would or wouldn't work, but on the surface it would appear the same.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

  • MrM1MrM1 Posts: 277Registered Users ✭✭✭

    do you have any idea if what I am doing will work with the SW inverter and the PSX-240 Auto transformer?  the post I posted at #34 here above starts to throw the idea into question.  

    But several months ago Schneider Tech told me yes it would work,   and yesterday Outback Tech told me it "should work but they had not tested it with the SW"

    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 23 #37
    Well the "deal" I found on the PSX-240 arrives tomorrow.  I originally was going to try an FW-X240, but decided I would be better off with the included box and breakers of the PSX-240 rather than trying to enclose the raw FW-X240 on my own.

    I do have some questions about wiring (and I will show my ignorance here).   Originally I had been looking at the manual and wiring for the FW-X240 raw transformer which seemed pretty straight forward.   This is from the manual for the FW-X240 for installing as a  Load balancing transformer


    This is the method I was planning on using.  It is not showing the Neutral to Loads ... but I assume this left out for simplicity?   A Neutral would come off the Neutral bus bar and run to each 120v L1 and L2 Load?

    *************************************


    But when I decided to go with the PSX-240,  there is no such wiring diagram in the manual.  Instead  the PSX-240 manual shows this for a Load Balancing set up ...



    Both of the examples above are directly from the OutBack Power Manuals for the FW-X240 and the PS
    x-240, But This wiring for the PSX looks kinda different from the one in the first example for FW-X.  

    Why is a 120 VAC show wire nutted to a Neutral coming off the L2 source?   

    In my desire to balance the loads can I just use the wiring diagram in the first example and wire the PSX-240 like the FW-X240?

    Does anyone know,  is the transformer in the PSX-240 electrical box  the same as the bare FW-X240??   

    Do I keep my system neutral where it is, connected to my neutral bus bar and simply connect the 2 neutrals of the auto transformer to the same bus bar? 

    Thanks
    Mike
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    My understanding is the bare transformer is the same as the one in the box with breakers etc.

    I think the diagram is showing the wire nut to the L2 live. The caption referencing neutral is just showing 120v from L2 to neutral, not saying to connect L2 to neutral. If the second diagram added a wire nut to L1, it would be essentially the same as the first?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 23 #39
    Estragon said:
    My understanding is the bare transformer is the same as the one in the box with breakers etc.

    I think the diagram is showing the wire nut to the L2 live. The caption referencing neutral is just showing 120v from L2 to neutral, not saying to connect L2 to neutral. If the second diagram added a wire nut to L1, it would be essentially the same as the first?
    Well I did say above I would be showing my ignorance,  but That's what I thought.  I plan to wire the PSX as shown in the first diagram.   Hopefully I can post some compare-and-contrast shots of the power flow before-after / with-without the PSX with the Schneider Conext SW Inverter. 

    If it works,  it is going to be a game changer for how I use the system.  It will bring me back to my original intent and design.  


    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 24 #40
    OK the OutBack Power PSX-240 arrived today.    It was sold as "new" on eBay,  but looked a little worn. It had clearly never been installed,  but there was some misforming of the case (not really dented, just misshaped) and there was corrosion/surface rust on the transformer housing and some of the neutral connections.   Everything else looked good.    My guess is it was stored in a shop or garage in S. FL with no climate control.
    Ok,  so on to the install.  Before I got too committed to it,  (if it doesn't work I can still resell it) I decided to do a temp install.  I used the install diagram that was shown above for load balancing / stacking of 2 Outback power inverters.    But I am using a Schneider Conext SW 4024 split phase inverter.  I believe it has a single transformer inside that yields and L1 and L2 giving the user 240v split phase.    The reason I am installing the Autotransformer is explained in post #1.
    Here is the Temp install

    Here is the Size of the unit



    I simply connected the Red wire winding 1 from the AT breaker to my L2 inverter output bus bar and the Black wire winding 4 from the AT breaker to my L1 inverter output bus bar.  connected the neutral of the AT  windings 2 and 3 to the neutral bus bar of the inverter.     So just 3 wires and a ground going to the inverter switch gear box from the AT box.
    Powered it up with no loads.  Every thing worked.   
    Added loads and here are the results while running AC Support mode and grid connection/support.  Not perfect,  but now AC support mode works almost perfectly with unbalanced 120v loads on the Conext SW Inverter. 

    Here is a 120v 1000w water heater element and my fridge both running on L1  without the PSX-240 AT using the Conext SW in AC Support Mode

    And With the PSX-240 AT


    Here is the fridge and some low voltage stuff.  Fridge is L1 and other stuff is on L1/L2.  Without PSX-240 AT using the Conext SW in AC Support Mode

    With the PSX-240 AT

    Not a lot of difference,  but the load in general is pretty low.  And the SW has to draw at least 2 amps from the grid at all times (when there is a load) so that it does not back feed the grid.

    Here is the Washer on L2 and the Fridge on L1 with the 240v well pump on the PSX-240 AT using the Conext SW in AC Support Mode





    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 24 #41
    So the end result is I believe overall positive.  I would say the PSX balances  the various 120v loads  that were unbalance, now drawing from both L1 and L2 of the inverter and allowing the SW's AC support mode to work more or less as advertised.   So in the end,  the PSX Autotransformer seems to make the North American version of the SW invert work more effectively using AC support mode. 
    I am happy with the outcome.


    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 24 #42
    mike95490 said:
     But why not wire that heater to 240V and spare a LOT of trouble? That heater is a huge imbalance and I'm surprised the inverter even tolerates it ...

    grainger has several 240V, 750 & 1,000 w elements, and then you could use a fairly smallish (lower losses) transformer,
    by shifting the big 120v loads, to 240V.  Maybe the microwave & blow dryer would need a larger transformer to support them but how many hours do they actually run, and is a $500 transformer worth $20 of electricity ?

    Funny thing @mike95490 ,  when you suggested it back in mid March,  I did just that.  I got the 1000w 240v element and it has been running fine.   UNTIL TODAY.  Oddly,  after I picked up the PSX at the post office,  I came home mowed the grass and with the PSX still in the box discovered I had no hot water ???? What?  I did not know it, but it had been out since yesterday.
    Upon testing I discovered the little element from Granger had already burnt up ??   Wow.  That thing did not last long.  So I installed a 240v 4500w element that I had and connected the water heater back up to 120v (which in theory gives me 1125 watts from the WH element - in practice its more like 1020w). 
    So the pics of testing above with and without the PSX  and the Water Heater are using the 120v water heater element.   And it is working really fine.  Now that i have the PSX-240 AT, I will probably keep the WH at 120v because the 240v 3000-4500w elements are much easier to come by.
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mike95490mike95490 Posts: 7,901Solar Expert ✭✭✭✭
    I'd send that element back to Grainger, it should have a +10 year lifetime
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    mike95490 said:
    I'd send that element back to Grainger, it should have a +10 year lifetime
    I might,  but it was only $7 and it was almost double for shipping.   So by the time I shipped it back I might not be ahead by much. 
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mike95490mike95490 Posts: 7,901Solar Expert ✭✭✭✭
    There may be a Grainger store in your area, if so, report the failure and exchange when you go into town.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • new2PVnew2PV Posts: 305Solar Expert ✭✭
    What kind of generator are you using?
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    Not using a generator at the moment.  Have a 4000watt one that is being rebuilt
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 26 #48
    I have done some more testing with the PSX-240 Autotransformer today.  Using a load on L1 only:
    • L1 load 1120 Watts
    • No Load on L2
    • Without PSX AT the SW drew nothing from the battery, whole load came from Grid
    • With the PSX AT it drew 740W from Battery and 380W from grid
    Ran some other loads with it,  and over all testing different loads and  balanced / unbalanced combinations,  I am getting about 66-70% of the load from battery/solar.  This is up from 0-11% without the PSX AT.
    I then compared the L1 only load with my 240v balanced well pump load by itself at 800W, and with the PSX AT on and the SW set in AC Support mode (same as the test above),  even the balanced load of the 240v well pump ran at about 69% from battery and the rest from grid.
    So I think the PSX-240 is doing what I had hoped it would do.  Perhaps not quite as well,  but still very good.  Especially since the SW inverter will require that the total system draw 2 amps from the grid at all times when loads are present.
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
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