Outback Inverters/ X-240 Transformer Causing Generator Damage?

AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
Hi All,

We recently inherited an "Orphaned" client with a fairly new system; 2-3024 Outback Inverters, an X-240 auto transformer (see config diagram), 2 MX-60s, full Outback Flex pre-wired AC and DC connection panels and breakers, 15 Mitsubishi 175 watt panels (five groups of three), and a 850 AH SolarOne 85P Battery array (two 12-volt boxes).

He likes to run portable backup generators for about 3 hours per day when he's pumping water, and he told us he's had two of these generators burn out already in less than six months. The first two units were from Costco, a 5,500 and a 10,000 watt Coleman. The first one lasted 6 weeks, the second one 3 days. Both failed suddenly with no output. He's now been on his third portable for one month, a Honda EP6500CXS 6,500 watt unit.

The generator failure issue was one of the main reasons he fired his original servicer and contacted us. The previous servicer had installed a 240 volt cord to the gennie, then returned to install a 120 volt cord so the owner could use a secondary 2,000 watt/120 volt gen in an emergency. From the get go tho, the 6,500 watt generator was having trouble with the inverter not locking on. The 120 volt hookup apparently worked as a backup but was only powering half the house because the other Inverter would shut down while this was running.

I checked the inverter settings and found that the AC2 IN on both inverters was set at 25 amps and the Charger amps were at 17.

I readjusted to both inverters to 14 amps AC2 IN and 14 amps max charger current. I also bumped up the max voltage limit slightly to 132 since the gen was running a little fast without load, preventing the inverter from locking on. Attempts to lower the gen speed caused the inverter to lose lock again but because the freq sagged under load below the cutoff. Finally found a happy medium.

That was about three weeks ago and all was working.

This morning the owner called and reported that his third generator is now not working. It runs but apparently has no output (checked breakers, etc. but no voltage tester). We'll go out and confirm what's really happening tomorrow but I told him I would perform some "Due Dilligence" first.

Are there any potential issues with the the prior setup, the current setup, or the Outback gear itself that could cause these generators to fail prematurly? I know portables are a bad bet for backup and I told the owner this. We're trying to convince him to install a Kohler 17RES power plant, but he's now worried it will burn up, too.
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,163 admin
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Alan,

    My first guess--the grounding between the genset and your inverter/charger/AC panels...

    You can end up with a ground loop if the neutrals and grounds are bonded to "earth" ground in several places (one in the AC fuse panel, another in the Genset, and possibly even issues with DC grounding between battery ground and other possible DC grounding).

    I know that the manuals tell you to earth ground your genset--and "proper" building code design requires you to safety ground at the panel.

    I would double check that the neutral connection at the genset is floating--before I were to ground the chassis.

    Also, I would check that their is only one "hard" DC ground for your DC system. You have potentially large currents circulating in your DC system (10-20 higher than in the equivalent AC side of your system)--and if there is a "parallel" current path for, say your DC battery to the Inverter DC ground, and a path for your AC ground from the Genset to the Inverter on the AC side--it is possible for those high currents to take the path of least resistance--which may include sending relatively high DC currents through your Genset's ground/neutral (and possibly your 120/240 volt windings????).

    The DC current flow can be difficult to measure--most people have AC current clamps to measure current flow--but DC will not show up. DC active current clamps are available--but more expensive and not many folks have them.

    You can take a DVM and connect (for example) between your AC or DC panel/battery ground and your genset ground/neutral...

    Put the DVM on AC--and see how much voltage you get (should be less than a few volts). Then put the meter on DC volts and see how much drop you get (should be well under a volt or two).

    (by the way, take your DVM, set it to DC 20 volt scale and put it on your car battery--some meters will measure 0 volts and others will measure ~12 volts... Different meters will behave differently. Some will simply put a cap in to block any DC voltage. Others really measure the "whole AC+DC voltage" and compute the RMS--root mean square--value. Both are useful--but it can lead to some confusion when tracking down AC vs DC current loops).

    Regarding the Coleman gensets--did you ever take one apart and see where the problem may be? The cheap gensets are not known for their long life (plastic bushings that fail, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Good information. Never thought about grounding being a potential problem.
    Actually, I do have a clamping DC DVM. We use it to check what's passing through the battery and PV cables.

    No ground at the gen. It's about 20' from the inverters and, of course, it's sitting on rubber wheels and bumpers. Any active ground loop would probably exist between the solar gear and the LC, located someplace inside the house.

    Not sure what kind of grounding is on the solar system or the load center but we'll check that. This is Mexico, so all US-based wiring assumptions are probably wrong.

    The owner took the old gensets back to Costco and got replacements. Before our time.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,959 ✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Your schematic looks odd, the way it is drawn the X-240 is in series with each load and not really sure what it would do as you have each phase essentially shorted to the other depending on the true phase difference between the two inverters.

    The typical use of an X-240 is one side get a hot and neutral, the other side then is 240V ( hot hot ) isolated and no connection to neutral at all, just the 240V load

    Also are the 120V outputs for separate loads?, are the inverters linked to provide 240V? ....

    You may need to step back and understand what the load wiring is a clean slate look at how it should be done, not how it was done
  • BB.BB. Super Moderators, Administrators Posts: 28,163 admin
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Outback has some sample schematics for their system (including the auto-transformer)--you can double check against those.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    I copied the diagram from the outback manual:

    http://www.outbackpower.com/pdf/manuals/fw-x240.pdf

    This wiring configuration is what was already there and I'll admit I had the same initial reaction you did. I don't fully understand how the transformer works in this configuration, but it looks like this is the configuration that Outback is recommending for this type of installation. See page 10. Apparently, it only loses a few watts in this type of configuration but gains system efficiency by allowing one inverter to "snooze" when the load is low.

    The Outback Inverters are configured in classic stacking to get 240 Volts.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    I would say that the combination of his water pump ( Size ? Type? PF ?) and the fx`s charging are just to much for a small gen,
    I readjusted to both inverters to 14 amps AC2 IN and 14 amps max charger current.

    be aware on the above quote, max charger current is how much ac is used to charge (this is also how you limit bat charge current)

    AC2 IN is maximum amp`s the LOAD AND CHARGER can draw combined, if it is reached, the charger is backed off (a little slowly at times as-well:-) it does not limit pass through current.

    Have a good one
    Tim
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Hmm, not sure I got that. When AC2 IN is limited to 14 amps, the Inverters are only going to pass through a maximum of 14 amps from each leg of the genset before they start inverting to handle additional loads above that, no?

    I thought 14 amps max per leg (1,680 watts ea - 3,360 total) should be within the capacity of a 6.5 Kw genset, regardless of what kind of equipment is running on it. Are you saying 14 amps per leg is too much because there is a pump running, with the charger using whatever is left?
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?
    Hmm, not sure I got that. When AC2 IN is limited to 14 amps, the Inverters are only going to pass through a maximum of 14 amps from each leg of the genset before they start inverting to handle additional loads above that, no?

    No, they can not limit pass through, only lower charge current to lower load, if they have backed off the charge to zero, it does not stop you drawing more than 14a through them,
    They do not switch to invert to support gen (some inverters do,called gen support on other makes)

    I would suggest having a look at the house loads and their balancing between legs, if this is poor , It can adversely affect ( the smaller the worse) gens, also causing voltage in-stability,


    What type and rated well pump ? for example the long thin bore-hole pumps are particularly bad, they can draw up to 10 times their rating to start ? What are the other house loads ?

    Have a good one
    Tim

    ps have you done the VBATT calibration ?


    __________________
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Sorry, maybe I have a complete misunderstanding on this point and need to confirm. Why would Outback Inverters have an AC2 IN limit adjustment at all if it doesn't limit AC2 IN? From the Outback VFX3648 Rev 7 Manual, Page 46:
    The AC2/GEN LIMIT is the maximum amount of current that the FX will allow to be drawn by AC loads and battery charger together from the generator. When this limit is reached the charger will be “backed off” to keep from overloading the generator. This setting has a range between 5.0 aac and 60.0 aac in 1.0 aac increments.
    What type and rated well pump ? for example the long thin bore-hole pumps are particularly bad, they can draw up to 10 times their rating to start ? What are the other house loads ?
    Owner says there are two 1 1/2 hp surface pumps, no well pumps.
    ps have you done the VBATT calibration ?
    No I haven't, but how would that have a bearing on the issue with the generators?

    Your comment about balancing house loads between legs, though, does make me think I need to check the programming for the stacking configuration to confirm if it's in "Classic" or "Outback" stacking mode. My understanding from the manual is that Outback stacking, together with the X-240 Xfmr, is supposed to do the load balancing dynamically when there is a mixture of unbalanced 120 and 240 volt loads, and that "Classic" stacking is not recommended for a mix of 120 and 240 loads.
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?
    Sorry, maybe I have a complete misunderstanding on this point and need to confirm. Why would Outback Inverters have an AC2 IN limit adjustment at all if it doesn't limit AC2 IN?

    It does limit it as much as it can , by turning charge down, It (or any other`s) can not limit pass through current,
    Owner says there are two 1 1/2 hp surface pumps, no well pumps

    can you get the ratings on the motor`s ? , Any other loads ? fridge etc ?

    If the VBAT is out , may contribute to gen un-balance,

    Have a good one
    Tim
  • BrockBrock Solar Expert Posts: 631 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Basically the limit only limits what the inverter will draw to charge the batteries, not what is passing through. So say you have no load the inverter will use all 14 amps to charge the batteries. Now say you have a load running pulling 10 amps, now the inverter will throttle back the charging to 4 amps and let the 10 amps pass through to the load. Now if you have a 15 amp load, the inverter just passes that through again, but stops charging to not add to the load. And if you have a 25 amp load, it still lets the full 25 amps pass though and still does no charging. Basically it will only start charging when the load side is less than 13 amps.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Yep thats what I am trying to say :D:D:D:D
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    OK, I'm still not getting this. I understand the battery charger limit being set at 14 amps and the inverter scaling back the charger as the AC load rises until it drops charging to 0 at 14 amps AC load.

    But why then have an AC2 IN limit setting at all if it doesn't limit AC2 IN?

    1. Let's say you have AC2 IN set at 15 amps and Charger Amps set at 10 amps. As the AC load increases to 10 amps, charger amps drop to 0. What happens when AC demand rises to 20 amps?
    2. Now set AC2 IN at 10 amps and Charger Amps at 10 amps. What happens when AC demand rises to 20 amps?
    3. Now set AC2 IN at 5 amps and Charger Amps at 10 amps. What happens when AC demand rises to 20 amps?
    4. Now set AC2 IN at 0 amps and Charger Amps at 10 amps. What happens when AC demand rises to 20 amps?
    If the inverter allows 20 amps to be pulled from AC2 IN in all four situations, then why have an AC2 IN limit setting at all? Why not just have the Battery Charger Limit?
  • blackswan555blackswan555 Solar Expert Posts: 246 ✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    It does limit AC, but only to the point of backing off charge, there is no way other than a breaker that switches everything off on over current to limit what load you put on the end of it,

    My conclusion is that you customer has had poor and undersized generators from day 1, they should be sized to cope with the max battery charging amp draw ( measured / pf compensated) plus the max of the house, take into consideration what fuel and altitude they run at, And de-rate accordingly, It`s not a good idea to run over 80% of capacity, and that is on a "proper" generator, not a cheep pile of poo, 3360w, 2 x 1 1/2 hp pumps for 3 hrs a day plus any quiet loads he forgets to mention, hmmm :blush:

    I would recommend installing some type of energy monitor before going much further, you can then tell the customer with confidence what will or will not work, ( I have had a similar customer, gen required was 3x what they were sure they needed, 2 yrs later they have so many new toys they are knocking 17kva over, doe :confused:)

    Have a good one
    Tim
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Another possible contributor, Outback's are very picky about generator frequency and manual actually mentions that unit is not intended to be used with generator.

    Pump starting surges may bog down generator momentarily and slow reacting Outback might be pushing large curents at the generator.

    Did you investigate the generator failure mode?
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?
    Did you investigate the generator failure mode?
    Sorry, could you explain what is "generator failure mode?"
  • BB.BB. Super Moderators, Administrators Posts: 28,163 admin
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    What "failed" on the genset--Burned out windings in the alternator? Burned out ground trace. Failed electronic voltage controller module?

    Does the alternator get good cooling or is it installed in a hot building with poor ventilation (security)?

    I know the two Costco gensets where before your time--what about the Honda failure?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rplarryrplarry Solar Expert Posts: 203 ✭✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    RCinFLA
    Actually it has been my experince that Outbacks FX and VFX's work very well with generators, but the GFX's are very picky about generator hz. I doubt Alans customer is grid tied. Just a guess on my part.
    Larry
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Heh, OK, wasn't sure if you might be referring to some new Outback Inverter feature :D

    No, I don't know yet what the issue is with the current gen. The owner took it to a repair shop up in La Paz and it's still there. I told him we really need to know specifically what the failure was. Must say that sometimes the information we get from mechanics here is highly suspect.

    The two previous gens were simply swapped out without diagnosis. Would have been nice to know what happened exactly.

    Yes, this is a total off-grid system. That's about all we do here.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,959 ✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Just a suggestion, but you should take this up at the Outback Forum if you haven't already.

    http://www.outbackpower.com/forum/

    they should have answers to better explain the AC amps limits and pass thru currents
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?
    Just a suggestion, but you should take this up at the Outback Forum if you haven't already.
    Yes, thanks, did that since it's 100% pure Outback. Must say, tho, still waiting for replies there. Help on this board is much higher.
    Does the alternator get good cooling or is it installed in a hot building with poor ventilation (security)?
    They were all located outside (Gasoline portables).

    We'll be installing an owner-supplied Kohler 17RES in a couple of weeks, also outside. Another reason why I want to be sure we cover as many bases as possible so we don't risk more fried gear.
  • BB.BB. Super Moderators, Administrators Posts: 28,163 admin
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    You probably have already done this--Have you measured the AC current on each leg of the genset (L1, L2, Neutral) with a True RMS reading meter?

    The alternators/wiring more affected current (Volts*Amps causing I^2 * R losses) than just the "watts" themselves.

    If you have something will very poor power factor (out of phase current from well pumps, non-linear current wave form from large battery chargers without power factor correction, etc.) can require a genset that is 2x the size of the true Watt loading (upwards of 2x the amount of current flowing through the wiring vs the true wattage requirement would seem to indicate).

    Sounds like the above should not be a problem... The Costco / Coleman failures may just be the nature of the beasts (cheaply built, not a long life expected).

    The Honda should have been better. But one stupid question about the Honda EP6500CXS. Looking around it appears that it may be a 220 VAC 50 Hz unit (real Honda Data Sheet seems to be hard to find for me). It is possible that Honda uses the same model name/number for 120/240 VAC 60Hz as 220 VAC 50Hz units...

    This does not make sense, because (as I understand) the Outbacks are wired as 120 VAC units with connections to 240 VAC split phase output.

    I am confused. :confused:

    It is strange--if all things were equal--I would be wondering why the smaller Outback inverters are not failing when driving the same loads (excluding the internal battery chargers).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    It has to be 60 Hz. The Outbacks would never lock onto it otherwise. Hard to imagine anyone in Mexico importing or selling anything here other than that...

    EDIT: No, wait, I'd better confirm that! A 50 hz /220 v generator with the speed turned up could look like a 56 Hz ~ 60 Hz gen outputting somewhere around 240 volts, no???

    Just got word back from the owner that the gen repair shop said there was a "bad relay" in the gen. I don't have any more than that. I'll have one of my guys call the shop directly to get the specific details as my Spanish isn't that good.

    But maybe we're getting somewhere closer. Does anyone have any info on what conditions could cause a generator relay to fail? Is this a generator "protection" relay? I'll continue to dig into this.
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?
    You probably have already done this--Have you measured the AC current on each leg of the genset (L1, L2, Neutral) with a True RMS reading meter
    Will check when the gen comes back from the shop. I have a pretty good Fluke TRMS clamper.
  • BB.BB. Super Moderators, Administrators Posts: 28,163 admin
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Honda usually has pretty good product manuals (shows the basic wiring between FRU's (field replaceable units). I have looked around--but cannot find any on-line/download for this model Honda Manual.

    Perhaps they can fax you the block/line diagram from the generator's manual (if they have one).

    Found a Honda brochure from Chile that shows it (or at least some versions) to be a 50 Hz / 220 VAC unit... Found others that said the same thing.

    Certainly possible that imported a "Latin America" unit with Spanish documentation--just cranked up from 3,000 to 3,600 RPM.

    Not sure where the relay comes into the issue... It is possible that there is a center tap for "safety ground"--and in your application it is being used as a Neutral--perhaps causing overheating of anything in that current path.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 28,163 admin
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Here is an example of the diagram for the EP2500 product manual (no relay that I saw in this simple manual start series)...

    Perhaps the relay they are talking about has to do with the electric start or low-oil shutdown.

    Found the Honda Mexico site:

    http://www.honda.com.mx/fuerza/index.php

    Says your customer's should be 120/240 VAC 60Hz:

    http://www.honda.com.mx/fuerza/fichas/gen_standard_ep6500cxs.htm

    Still no on-line manuals. :confused: (that I could fine)

    The EP line appears to be made (and designed?) in China--possible that it may not have the Honda quality of their other product lines.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    Hello BB,

    Thanks. I was just on that Mexican site reviewing the info when you posted. Was relieved to see it wasn't 50 Hz but, yes, no manual, and not much else there either. I do have the listings for the two distributors in BCS and will follow up with them.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?
    2-3024 Outback Inverters, an X-240 auto transformer
    The Outback Inverters are configured in classic stacking to get 240 Volts.
    This combination is a no-no. Either take out the X-240 and leave the inverters set up as a “classic stack” (two inverters in “series”), or leave the X-240 in and use the Mate to change the “slave” inverter from “Classic” to “OutBack”.

    HTH,
    Jim / crewzer
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    My wrong. It's configured for Outback stacking.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Outback Inverters/ X-240 Transformer Causing Generator Damage?

    OK. I'll look back through the thread and see If I can sort this out. Gimme a few days... In the meantime, can I ask for some additional info? Specifically, what are ambient daytime temps for the system's location, and what is the altitude?

    Also, please double-check the inverter model numbers... the 3024 is usually an "export" model (VFX3024E) rated at 230 VAC/50 Hz, 3,000 VA.

    Regards,

    Jim / crewzer
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