XW+6848 Adjusting Output Voltage?

ColoradoSolar · October 2017

I have a new off-grid system I just brought on-line that includes an XW+6848. The output voltage is 117/235. I was wondering if it is possible to adjust the voltage higher? I know it is within the XW+6848 specs of +/- 3% but my solar room is in the barn about 100' away from the house so I would like to compensate some for the voltage drop getting to the house.

Thanks,
Eric

WaterWheel · October 2017

I've got a 6848 about 6' from the Conext battery monitor shunt and reads 122v or 244v with both lines feeding, 70' from the control panel (Conext), and about 250' from the pump. Having said that I'm not aware of any ability to adjust the output voltage. I haven't checked the voltage at my 1.5hp pump but it seems quite happy with the 6848's power.

I suspect most 240v pumps are quite happy at 230+v. Only been running my 6848 for two years but I suspect I may have a bit more inverter than I needed since the pump was the defining load and draws about 2300 watts.

A thought from another thread you've got. I started with a Magnum PT-100 controller but quickly learned that having a Conext controller worked better with the Conext control panel for fine adjustments to the charging routine.

Dave Angelini · October 2017

WaterWheel is correct. There is not any user adjustability and voltage loss should be addressed in wire sizing.
The actual voltage is adjusted internally dynamically by the XW and there is firmware that can be written for this.
Schneider will not want to bill you to write firmware that would void your warranty and so we are back to wire sizing.
The XW is a DSP device and almost everything is adjustable. I hope this helps.

ColoradoSolar · October 2017

Dave Angelini said:

WaterWheel is correct. There is not any user adjustability and voltage loss should be addressed in wire sizing.
The actual voltage is adjusted internally dynamically by the XW and there is firmware that can be written for this.
Schneider will not want to bill you to write firmware that would void your warranty and so we are back to wire sizing.
The XW is a DSP device and almost everything is adjustable. I hope this helps.

Well it answers the question but doesn't help.

It's not so much voltage loss in the cable as it is "low" voltage to begin with. I have a coffee roaster that the very picky about the voltage, so even if I were to run it in the barn I would love for the voltage to be closer to 120.

Dave Angelini · October 2017

Image: https://us.v-cdn.net/6024911/uploads/editor/lh/kpz8u8fpqzcl.png

You have something else wrong if your appliance is that sensitive in my opinion!

ColoradoSolar · October 2017

Dave Angelini said:

You have something else wrong if your appliance is that sensitive in my opinion!

I don't disagree, the roaster was cheaper than the others but it didi a good job at my last house (on-grid), except in the summer when everyone was running their AC. It did not like the off-grid system that came with my current house. I haven't tested it on the new system yet, since I just got it running yesterday. If it doesn't work well on the new system then I will look for a new roaster because I really like my new Conext system.

MichaelK · November 2017

I'm also using a XM6848 to power my 1.5hp well pump. The voltage is also a bit low, 235VAC. I've also noticed something that might be relevent to the topic. Until this year, I powered the well pump with a 6kw gasoline generator. Over the years I've kept detailed records as to starting and stopping times, gallons of water pumped, and gallons of gasoline consumed. My long-term overall average for pumping water works out to be ~275-280 gallons per hour, based on 6-8 hour runs. The running amperage while under generator power was 10.0amps at exactly 240VAC.

Now that I'm powering the well with the XM, my water output has climbed to ~320-325 gallons per hour. It's only a 15% increase, but uniform from day to day. I would interpreate this as the pump motor running more smoothly on "cleaner" AC produced by the XM, compared to the generator. It's still drawing 10.0 amps as indicated by my Fluke clamp.

cow_rancher · November 2017

MichaelK said:

Now that I'm powering the well with the XM, my water output has climbed to ~320-325 gallons per hour. It's only a 15% increase, but uniform from day to day. I would interpreate this as the pump motor running more smoothly on "cleaner" AC produced by the XM, compared to the generator. It's still drawing 10.0 amps as indicated by my Fluke clamp.

Many things affect your GPM rate, the most obvious would be a rise in the static water level in your aquifer, how deep is your well, and how deep is the static water level, and is that the vein of gravel/sand where you are getting your water from, it all makes a difference.
I would not think that the power provided by the XM is any better/worse than the generator, after all the generator is putting out a true sine wave, whereas the XM is reconstructing a true sine wave. You can get better answers from a well forum, I use the guys at http://www.pumpsandtanks.com/ to answer questions, as they don't try to sell you something that you don't need.

Rancher

mike95490 · November 2017

i'll disagree with generators being inherently "cleaner". I have 2 gensets, both have waveform issues. 1 has pi$$ poor power factor and can barely run my pump, which, being a large (1/2hp)

Image: https://us.v-cdn.net/6024911/uploads/editor/am/hqmcamqikjyw.jpg

motor, has poor PF.

MichaelK · November 2017

cow_rancher said:

Many things affect your GPM rate, the most obvious would be a rise in the static water level in your aquifer, how deep is your well, and how deep is the static water level, and is that the vein of gravel/sand where you are getting your water from, it all makes a difference.
Rancher

I think statements about water level and the depth of the well are totally irrelevent to the discussion at hand. If I'm pumping water at 275 gallons per hour on Saturday with the generator, and 325 gallons per hour on Sunday with the inverter, then I think that has something to do with the inverter. I've been pumping water out of this well for 10 years now, so I think I should know how my well behaves.

Dave Angelini · November 2017

With all of your experience I would think a 15% difference would not be a big deal, as you said.

I think cow_rancher and Mike were just trying to help you. If you look at the waveforms on an oscilloscope you might find out quite a bit. There is an error in a clamp-on that is not there with a shunt current measurement also.

MichaelK · November 2017

Dave Angelini said:

If you look at the waveforms on an oscilloscope you might find out quite a bit. There is an error in a clamp-on that is not there with a shunt current measurement also.

Yes, that is exactly my plan. I picked up this Leader 522 at a local swap meet that I plan on using to look at waveform.
https://www.facebook.com/photo.php?fbid=10214356286765535&set=a.2407166143060.2141275.1368382807&type=3

cow_rancher · November 2017

mike95490 said:

i'll disagree with generators being inherently "cleaner". I have 2 gensets, both have waveform issues. 1 has pi$$ poor power factor and can barely run my pump, which, being a large (1/2hp) motor, has poor PF.

I think that the generators inherently have a cleaner waveform since they are not a modified sine wave created by step voltages smoothed out by an inductor-capacitor network. Now poor Power Factor is another thing, and good generators will have a PF of .9 or better, and it really is dependent on the load, at the copper mine I worked at the mine's head electrical engineer loved the synchronous motors we had on the ball mills because we could adjust the PF to zero out the rest of the motors on the pit.

Rancher

mcgivor · November 2017

The waveform of both inverters and generators can be either clean sine wave or dirty sine wave, the quality of the device determines what it produces, cheap versions of both can have total harmonic distortion so high, the output hardly resemble pure sine wave, so a blanket statement claiming one is better than the other can't really be made with confidence, the old adage you get what you pay for( although not always ), comes to mind. Link shows some scope images as examples http://www.jkovach.net/projects/powerquality/

MichaelK · November 2017

mcgivor said:

Link shows some scope images as examples http://www.jkovach.net/projects/powerquality/

Yes, thank you! Exactly what I was referring to. Now that I have my new toy, I can confirm this for myself.

Will get back to you later on this

BB. · November 2017

Be careful with the o'scope....

Most scopes have the ground clip of the probe connected to the chassis ground of the scope (and the ground prong of the AC plug). The input is not "isolated".

It is easy to create a short between AC hot and ground if you are not watching what you are doing and/or do not have the right equipment to make the connections.

If you want just one trace to show (for example) voltage--You can connect AC1 to probe A, and AC2 to probe B, set probe be "invert" and Add A+B. Just clip the two probe ground together and to nothing else.

If you want to measure both current and voltage--You might do OK with just connecting AC1 Hot to Probe A, and leave the ground clip unconnected. And use probe B for the current probe (with a current transformer or possible a current shunt/precision resistor in the neutral lead).

Ideally, you want active differential probes for 120+ VAC to provide isolation between AC mains and the o'scope. However, these are not usually cheap ($600=>many thousands of dollars). There are some "scope systems" that may be less, but may not fit standard BNC scope connections. Or isolated AC input capable o'scopes.

Otherwise, using an 120 VAC rated isolation transformer (i.e., 120 to 12 VAC) and connecting your probe to the 12 VAC output would work fine--The question is the "band width" of the AC transformer (would it filter out the higher frequency waveform distortions)?

Generally, an AC current probe works nice:

https://www.ebay.com/sch/items/?_nkw=oscilloscope+ac+dc+probe

We also used to use an AC isolation transformer to "float" the scope, and then connect the probe signal and ground leads as needed... But that does (usually) make the scope chassis "hot".

Anyway--Be very sure of what you are doing.

-Bill

ColoradoSolar · November 2017

Just wanted to update this thread. Turns out there is an easy way to change the output voltage on the Conext system, it just takes the $600 Conext Configuration Tool. Luckily tech support at Schneider was nice enough to loan me one. Once it arrived I quickly had the voltage to the right level. All without voiding my warranty

Dave Angelini · November 2017

Wow, what is the range?

ColoradoSolar · November 2017

Dave Angelini said:

Wow, what is the range?

I don't know what the range is because the number you change starts at something like 32355. So I'm assuming it is some sort of divisor for a PWM that creates the output voltage. But if on my system 32355 ended up being 235v then I am assuming that is has a large range, don't know if the transformer would like it though.

Dave Angelini · November 2017

Was there a service note? Did this actually change the output voltage? The reason I ask is 235V is pretty close to what they normally come out as? Are you sure you are not just changing the range of acceptable limits for high and low line? That is a common adjustment. The voltage does move around with load, heatsink temp, and ambient. It is a dynamic setting.

I have had the config tool since 2006 and never noted this, it does not surprise me though. Do you have combox?

ColoradoSolar · November 2017

Dave Angelini said:

Was there a service note? Did this actually change the output voltage? The reason I ask is 235V is pretty close to what they normally come out as? Are you sure you are not just changing the range of acceptable limits for high and low line? That is a common adjustment. The voltage does move around with load, heatsink temp, and ambient. It is a dynamic setting.

I have had the config tool since 2006 and never noted this, it does not surprise me though. Do you have combox?

235v is the voltage mine started out with. I changed it to a bit north of 240v. That way I don't go as low on the voltage once my large loads kick in.

I do not know if there was a service note, I got my info directly from tech support. The setting is briefly described in the manual for the config tool (don't have the page number right off hand) https://41j5tc3akbrn3uezx5av0jj1bgm-wpengine.netdna-ssl.com/wp-content/uploads/2016/12/conext-configuration-tool-ai-owners-guide-975-0721-01-01-rev-c.pdf

It did actually change the voltage, it is absolutely not just changing the high/low limits.

I do have a Combox but according to tech support changing the output voltage is one of the settings that can't be changed on a Combox. You have to use the configuration tool.

Dave Angelini · November 2017

OK sounds like for real to me. Good info! The combox is why I doubted you as it is not in there. Probably a good thing also.

The history on the configtool was to keep non informed users out of shutting down an offgrid inverter. Since there was very little reason to change firmware for Offgrid applications it makes sense that there are settings that Schneider keeps closed or does not have documentation for the outside.

Usually AC voltage sags are from the DC side sagging BTW. You ok there?

ColoradoSolar · November 2017

DC doesn't seem to be sagging. I don't think the sagging is on the output of the inverter I think it is wire loss in the house which unfortunately I can't fix because all the wiring is in the spray foam in the walls.

XW+6848 Adjusting Output Voltage?

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