Xantrex XW6048 Gen Support

keyturbocarskeyturbocars Posts: 375Solar Expert ✭✭
I haven't posted for a while, but I've been coming here periodically and reading up some without logging into my account. Anyway, today, I was experimenting with my XW6048 inverter, and had a few questions that some of you more experienced with Gen Support. I've searched the forums and read what I could find and read the good info from Chris Olson on the topic.

I've got a low hour Onan 6DJE 6kW diesel generator feeding into AC2 input on the XW6048. My battery bank is a relatively small 600Ah 48V bank. I live on grid and I only have my system as emergency backup power. I was experimenting today with Gen Support. In the past, I didn't have much luck with it and there was so much light flickering in the house and clicking on the AVR's on some of my equipment, that I just abandoned the Gen Support testing. Back then, I didn't have the governor on the DJE set precisely enough, and I was up around 62-63Hz with no load. I recently adjusted the governor to get around 61Hz under no load and still maintain really close to 60Hz under full load (around 59.5Hz at full load). After adjusting the governor, I decided to experiment with Gen Support some more on the XW6048. I turned off all the big 240V loads and just selectively ran them one at a time. For example, I'd turn on the water heater (4.5kW) for a while when I knew family members were going to be taking showers. Then I'd flip that off and run the heat pump to cool the house for a while. I could run all the 120V loads in the house (approximately 1kW continuous loads) no problem and the big 240V loads one at a time, but the surge load of the heat pump kicking in would cause the XW6048 to drop generator input on AC2 and the inverter would take the full load and then a little while later the XW would switch back to the generator and it would take over again while the heat pump was running. When the heat pump kicked in and the XW6048 didn't like the generator input from AC2, the lights in the house would really flicker and the UPS on my computer would really complain for a moment while the XW6048 inverter dumped the generator input and picked up the entire load itself. After experimenting with some different Gen Support Amp settings, I settled on 21A so the generator would take up to 5kW of the loads and then the XW6048 would share the load above that.

By the way, I've got a 15 year old Trane 3 ton heat pump and my air handler has a 3/4HP blower motor. The Trane does have an aftermarket "soft start" capacitor kit on it. I know that it's asking a lot for the Onan 6kw generator to kick in that big of a load without a hiccup. As expected, the 4.5kW resistive load of the water heater kicking in is not a big deal. The surge load of the heat pump is what causes the most trouble. I have grid power and in a real life situation where grid power might be off for a while, to conserve fuel I would not plan to run my heat pump for an extended outage unless it's 100F or something. The easy solution to all this is to not expect to run the heat pump with such minimal backup power.

I checked the default AC2 AC Settings in the XW6048 and they are very forgiving in terms of the voltage and frequency ranges that are acceptable. Voltage input of 80-138VAC seems very lenient. Frequency of 55-65Hz seems very forgiving as well. I'm not sure why the XW6048 dumps the gen input because it happens so fast and the heat pump periodically cycles on/off that I haven't been able to observe the AC2 voltage and frequency when heat pump kicks in. I'd find it hard to believe that the voltage is sagging to below 80V. Perhaps the frequency dips below 55Hz for a split second as the generator bogs under the surge load of the heat pump compressor and blower motors.

1) Anyone have any tips or setting changes to try to minimize the generator input at AC2 on the XW6048 from being dropped when the heat pump starts?

2) Also, does anyone else notice their LED lights flickering while running on generator power?

My CFL bulbs don't seem to flicker but all the LEDs in the house seem to flicker when running on generator AC Pass Thru on the XW6048.

Finally, I did install a Flight Systems voltage regulator board on my Onan 6DJE because the original VR board was fried when I bought the generator. I did adjust the Flight Systems board to try to get the best balance of generator load and stability according to the instructions that came with the AVR board. Maybe I need to try to richen up the mixture and add some more diesel on my DJE under surge load. Not sure how to do that, but perhaps that would help the generator to pick up sudden surge loads more stably.

Thanks for any tips you might have,

Ed

Comments

  • mike95490mike95490 Posts: 7,964Solar Expert ✭✭✭✭
    Re: Xantrex XW6048 Gen Support

    I have issues with the gen support dropping unbalanced 120VAC loads, but not with the 240 welder or 1/2 hp pump. Just got my Conext ComBox and want to play with that this weekend.
    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 ,

  • inetdoginetdog Posts: 3,123Solar Expert ✭✭✭✭
    Re: Xantrex XW6048 Gen Support
    mike95490 wrote: »
    I have issues with the gen support dropping unbalanced 120VAC loads, but not with the 240 welder or 1/2 hp pump. Just got my Conext ComBox and want to play with that this weekend.
    You may just have to go with an autotransformer for balancing if you cannot find an adjustment for allowed unbalance.
    Can you tell whether the problem is the generator going out of regulation with the unbalanced load or the inverter getting upset on its own?
    The inverter could either try to handle all of the unbalance on its own, which might not be possible, or shrug off the whole unbalance onto the generator, which might make it unhappy. Be sure to determine which it is doing. Fortunately you can do this just by measuring the generator amps on each phase.
    SMA SB 3000, old BP panels.
  • NorthGuyNorthGuy Posts: 1,925Solar Expert ✭✭
    Re: Xantrex XW6048 Gen Support
    1) Anyone have any tips or setting changes to try to minimize the generator input at AC2 on the XW6048 from being dropped when the heat pump starts?

    I found that my generator regulates way worse when it is on the edge of capacity, and XW regulation of the loads is not very precise. So, I had to lower the AC2 settings to avoid overloading. It works Ok now.

    I have narrower voltage range for the generator, but much wide frequency range.
    2) Also, does anyone else notice their LED lights flickering while running on generator power?

    Generator power is going to loads in pass-through mode, so it doesn't depend on XW. All LED lights are different. Many will flicker when power is not good (meaning different from what the engineer expected).
  • keyturbocarskeyturbocars Posts: 375Solar Expert ✭✭
    Re: Xantrex XW6048 Gen Support

    Thanks for the replies.

    NorthGuy, what range did you program in for the AC2 frequency?

    I tried dropping the low end of the frequency to 52Hz on AC2 but the XW6048 still dropped the generator input when the heat pump kicked in. Maybe I should lower it a little more to 50Hz.

    I wonder if part of my problem might be that my XW6048 is normally in standby mode (--- is in the display on the front of the XW) since my Gen Support Amps is set to 21A. Then when the heat pump kicks in, the XW is too slow to respond to help carry the surge load and so the generator bogs too much under the large load and the XW doesn't like the incoming power so it drops AC2 all together. Makes me think that I should see if I can change Search settings or something to make the XW quicker to respond to the heat pump turning on. Might have nothing to do with my problem, but it was a thought that came to mind.
  • NorthGuyNorthGuy Posts: 1,925Solar Expert ✭✭
    Re: Xantrex XW6048 Gen Support
    NorthGuy, what range did you program in for the AC2 frequency?

    I have 100-135V and 50-70Hz for both generators. I'm not an expert in generators, I just found the settings that keep them qualified through everything and at the same time are as narrow as possible.
  • keyturbocarskeyturbocars Posts: 375Solar Expert ✭✭
    Re: Xantrex XW6048 Gen Support
    NorthGuy wrote: »
    I have 100-135V and 50-70Hz for both generators. I'm not an expert in generators, I just found the settings that keep them qualified through everything and at the same time are as narrow as possible.

    OK. Thanks for sharing your settings, NorthGuy.

    Does anyone know if the XW6048 uses something other than Voltage and Frequency to decide whether or not to drop an incoming AC source?
  • ChrisOlsonChrisOlson Posts: 1,807Banned ✭✭
    Re: Xantrex XW6048 Gen Support

    It only evaluates AC voltage and freq to qualify or disqualify the generator. When the big surge load hits the XW expects the generator to be able to handle the surge up to the AC2 Breaker Size setting, and maintain voltage and freq within spec. It is voltage that drops severely when the surge load hits, and frequency a little bit. The XW is disqualifying the generator because its AVR and governor do not react fast enough.

    You can minimize that problem by setting the allowable voltage as low as it will go, and increasing the AC2 Breaker Size to what the generator can handle on surge and maintain freq above 55 Hz. If the gen can't maintain 55 Hz under surge load, then its output voltage drops anyway, and it "cascades" into an overload, and the inverter takes over before the voltage gets so low that the amps increase beyond reason.

    AC motor's speed is determined by frequency, not voltage. So as long as you maintain 60 Hz the motor will maintain speed and the voltage can go down into the 90's and the amount of amps the motor pulls will just increase accordingly.

    The XW just compensates for this by taking over to prevent damage to your stuff, then re-evaluates the generator output for a bit before reconnecting it to the load, and loading it to the Gen Support amp setting.
    --
    Chris
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: Xantrex XW6048 Gen Support
    Does anyone know if the XW6048 uses something other than Voltage and Frequency to decide whether or not to drop an incoming AC source?

    :confused:It must be getting too late in the day because I have to ask: what else would it use? Those two pretty much describe the quality of an AC source (THD would be a function of both, so to speak).
  • ChrisOlsonChrisOlson Posts: 1,807Banned ✭✭
    Re: Xantrex XW6048 Gen Support
    :confused:It must be getting too late in the day because I have to ask: what else would it use? Those two pretty much describe the quality of an AC source (THD would be a function of both, so to speak).

    Well, you can also have phase angle problems with split-phase power with poorly wound gen heads. And you can also have problems with leg overload on split-phase systems when L1 or L2 load on the generator will exceed the breaker size, even though the total output of L1 and L2 do not exceed the generator's rated output. So the XW COULD disqualify a generator based on that. But it doesn't. Gen Support in the XW "kicks in" based on the highest loaded leg. And its charger also adjusts its output based on the highest loaded leg. This is necessary to prevent leg overload of the genset.

    The only way to get away from all these potential problems with split phase power is to use an auto transformer to balance the generator - and preferably the inverter too. The XW is beast, and it will handle huge leg imbalances, even well beyond the maximum continuous output rating of the inverter up to 75% difference between L1 and L2. However, generator's won't - try that with a generator and it will blow the breaker on it.

    Things get more complicated x 2 when you go from straight 120V single phase to split phase power.

    So it was a legitimate question. With a 120V single phase inverter - yeah, there's nothing else to look at other than voltage and freq. With split-phase power, there's a lot of things the XW COULD use to qualify or disqualify a genset. But it basically treats its AC2 input qualifications like two separate 120V single phase generators that are running 180° out-of-phase with one another, and it limits things based on the highest loaded generator.
    --
    Chris
  • keyturbocarskeyturbocars Posts: 375Solar Expert ✭✭
    Re: Xantrex XW6048 Gen Support

    Thanks a lot for the helpful info, Chris. I just tweaked the AC2 settings some. Since my original post, I also discovered that there is an adjustment for governor sensitivity on the DJE that is supposed to help with responding to big loads. I haven't had a chance to try that yet. The Onan manual says to adjust the sensitivity as much as possible to handle big loads but not so far as to cause RPM fluctuations under low/no loads. I'll have to play with that adjustment and see how it goes. I have a 240V air compressor in the shop with a big 6HP motor that really makes the DJE groan when the compressor kicks on. The DJE can kick it off and handle it, but the lights in the shop really flicker with my current governor settings. That might be a good load to use when adjusting the governor sensitivity to see if I can improve the responsiveness of the old Onan.

    I just checked the tag on the Emerson motor on my compressor. It lists running amps as 15.0A which equates to 3,600 watts. The label on this motor lists Locked Rotor Amps as 93A. That would be 22,320 watts. In any case, it really makes the DJE work hard to start it off. This particular DJE has the extended stack and I've read that it can handle up to 18,000 watts surge. Not sure if a surge of 22kW is for real on this 6HP compressor motor, but this Onan 6kW genset can start and run it.
  • ChrisOlsonChrisOlson Posts: 1,807Banned ✭✭
    Re: Xantrex XW6048 Gen Support
    Thanks a lot for the helpful info, Chris. I just tweaked the AC2 settings some. Since my original post, I also discovered that there is an adjustment for governor sensitivity on the DJE that is supposed to help with responding to big loads.

    Yeah, that's the governor buffer screw. The downside to making the engine react faster to loading with the buffer is that it's going over-react when you remove load. So if the genset is powering a load that has it loaded to say 80-90% rated, and you suddenly remove the load, it will overshoot and the XW will drop it because the freq goes too high.

    So before you mess with it, mark it or measure it so you can adjust it back where it was if it doesn't work.
    --
    Chris
  • keyturbocarskeyturbocars Posts: 375Solar Expert ✭✭
    Re: Xantrex XW6048 Gen Support

    That's good to know. I better keep track of how much I move the governor sensitivity adjustment wheel so that I can return it to the original setting if needed. After adjusting the governor, I might need to spend some time adjusting my AVR board again. I spent a lot of time with the Flight Systems AVR tweaking the setting to try to get good response and stable output. Sometimes it takes a long time to find the perfect balance, or at least I tend to spend a long time trying to get things to work perfectly.
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