AC output back feed

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AC output back feed

Postby Jtf on Sat Nov 11, 2017 9:47 am

I have 2 -3648 48Volt inverters 12 years old , have red light on # 2 inverter , mate reads error - AC output back feed, half my house has no power along with my 220 3/4hp water pump , any thought on how I can trouble shoot & get back on? Other inverter seems to be working fine
Jtf
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My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby Mike Curran on Sat Nov 11, 2017 10:05 am

The manual describes AC OUTPUT BACKFEED error as follows:

"Indicates that another AC source was connected to the AC output of the G(?)FX (you haven't spec'd your exact inverter model). Usually this is an installation issue. It often occurs when there's an X-240 transformer in the system that hasn't been installed properly. Also, check that there are no connections between the FX AC input and AC output circuitry."

If your system had been running normally up to getting this error and you haven't done anything to your house wiring that could've caused the error, I'd suspect an internal fault in your inverter.
Mike Curran
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Posts: 339
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: AC output back feed

Postby Jtf on Sat Nov 11, 2017 10:18 am

Thanks Mike, my inverters are FX models , I had this same problem a couple weeks ago I turned on my 20 kw generator for an hour and after I turned it off the red light went off and my power came back on but this time power to 1/2 of house is not coming back on. Would a short in the wiring some where be the cause, but no breakers have been tripped.
Jtf
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Posts: 7
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My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby Mike Curran on Sat Nov 11, 2017 10:26 am

When the error cleared from shutting off your generator - makes me think there was a connection between your genny and your loads in the house. I'm assuming your generator is normally connected to the INPUT side of your FX's, correct?

Now that the error is on steady (regardless of gen operation) don't know what to think. I would look for a wire that came loose or insulation wore through such that you got a short between the AC in and OUT of your inverter.
Mike Curran
OutBack Guru
 
Posts: 339
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: AC output back feed

Postby Jtf on Sat Nov 11, 2017 10:34 am

Yes generator hooked up to input side of FX
When generator is on all power is on in house, only when I turn generator off I have only 1/2 power in house
Jtf
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Posts: 7
Joined: Sat Nov 11, 2017 9:25 am
My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby Mike Curran on Sat Nov 11, 2017 10:43 am

When the generator is running both your inverters are in pass thru mode, but the one with an error probably isn't charging your battery...hmm. I would still look for a shorted wire between AC in and out on the fault inverter, wiring compartment or wherever it's located. Perhaps vibration from the nearby generator caused it?
Mike Curran
OutBack Guru
 
Posts: 339
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: AC output back feed

Postby Jtf on Sat Nov 11, 2017 11:21 am

Would I take off inverter panel to check for short or check for short between inverter & house? Also my batteries are reading 59.2 so seems like they're being charged by both, not sure though
Jtf
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Posts: 7
Joined: Sat Nov 11, 2017 9:25 am
My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby Mike Curran on Sat Nov 11, 2017 11:48 am

I wouldn't think that FX with error would be charging...could be wrong, tho'. You might get a full charge with only one inverter working anyway.

Short would be somewhere on either side of breaker supplying AC in (generator in) to faulted inverter, and AC out of that inverter. AC out is your house wiring (the half that's not working when genny is off); not sure what you've got on "AC in" side, probably not much if generator is your only AC input. You're looking for a connection between these two points that shouldn't be there. That's why I thought maybe insulation worn through or something like that.

I guess you could shut everything (including battery in to the inverters) off, then (1) take an ohmmeter and read between in and out of the suspect FX with the in and out breakers open. Not sure but expect if FX is okay, you should read some resistance there. If the FX appears not to be shorted internally, (2) close the output breaker to the house, measure ohms again. If close to zero, then something in house is back feeding (somehow) to the FX input, probably somewhere physically close to the FX. If reads high ohms, house side okay. (3)Try opening house side breaker of FX, closing genny side, read ohms again. If close to zero then genny side is shorted.

Hopefully you'll find a short external to the FX. Otherwise, it's probably your inverter... :sad:
Mike Curran
OutBack Guru
 
Posts: 339
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: AC output back feed

Postby Jtf on Sun Nov 12, 2017 8:50 am

Hi Mike ,with generator off, I turned all breakers off, then turned on inverter breaker on at mate, red light did not come on, I started turning all small breakers on to house , still no red light and I have power to all of house. I have a double pole 50 amp breaker coming from generator, when I turned that on the red light came on and I lost power to half my house. So I turned of 50 amp breaker and off and on breaker at mate and power came back on in all of house. So I “elimiatetd and conquered”, but now I have to find out what’s wrong between 50 amp breaker and generator? Does this mean inverter is ok?
Jtf
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Posts: 7
Joined: Sat Nov 11, 2017 9:25 am
My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby Mike Curran on Sun Nov 12, 2017 9:37 am

Jtf wrote: I have a double pole 50 amp breaker coming from generator, when I turned that on the red light came on and I lost power to half my house. So I turned off 50 amp breaker and off and on breaker at mate and power came back on in all of house. So I “elimiatetd and conquered”, but now I have to find out what’s wrong between 50 amp breaker and generator? Does this mean inverter is ok?

Was the generator running when you turned the 50A breaker on? If so, my guess is the inverter's the culprit. If not, your generator has somehow gotten itself connected to your house wiring directly - probably not likely :cry:
Mike Curran
OutBack Guru
 
Posts: 339
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: AC output back feed

Postby Jtf on Sun Nov 12, 2017 6:10 pm

Yes generator running when I turned 50 amp double pole breaker on, now Red light comes on on both inverters? Does it still sound like inverter problem? Should I replace
Boards on both inverters?
Jtf
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Posts: 7
Joined: Sat Nov 11, 2017 9:25 am
My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby Mike Curran on Sun Nov 12, 2017 7:19 pm

Something weird going on, what with both inverters showing the error when before it was just one. Now I'm not so sure it's the inverters. Does your generator wiring run in same conduit or raceway as some house wiring? Asking because of possible short there.

I'm really at a loss to explain this especially with the change. Something else is happening, I doubt both inverters would go bad at the same time. Has anything else changed recently? Don't know what else to suggest...
Mike Curran
OutBack Guru
 
Posts: 339
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: AC output back feed

Postby JRHill on Thu Nov 16, 2017 11:38 am

I recently stressed this in another thread - excuse if not applicable but I reiterate for others in the future:
--
Always let your inverter do what was designed to do: with your AC input DROPPED, connect the breaker, energize or whatever. Watch for errors. Let the genset stabilize and warm. Then set the AC INPUT to USE and watch that all transitions to the generator. As an added note, if the generator hasn't been run for a while, maybe tighten up the voltage/parameters, just in case. Stuff happens. In my case, mice.

At disconnect I believe its even more important to shut down the AC input via the inverter. Never, never just kill the power. Your Outback inverters have been made to watch incoming AC, not to mention the other Outback components, and transition/work together. Let them do what they've been made to do. And use your intuition - if there is a possibility of loads coming on or off at about the same time then don't do the transition until things are consistent.
--
If you're off grid, Dorothy, you're not in Kansas any more. Protect your devices with good habits.

Best,
Jim
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My RE system: -House: FM 80, VFX 3648, FlexnetDC, FlexWare xformer, Mate 3 / Hub, WattPlot/, 2925w SunTech 195, Trojan L16RE-B Batteries. Backup 1: Champion 75531i 3100, backup 2: 11kw Miller Bobcat;
-Well: Grundfos 11-SQF-2 pump, controller & AC switch (CU200, IO101), Morningstar 15a/48vdc Controller, 780w SunTech 195, Trojan golf cart batteries.
-All running since July '11 with no critical problems.

Re: AC output back feed

Postby Jtf on Mon Nov 20, 2017 7:44 am

Hi Jim thanks for the input, when you say dropped , does that mean the ac power is shut off & you say to turn off power at breaker on inverter rather than at mate , I thought it’s better to turn off at mate?
Jtf
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Posts: 7
Joined: Sat Nov 11, 2017 9:25 am
My RE system: 2 Outback 3648 inverters 48V

Re: AC output back feed

Postby JRHill on Mon Nov 20, 2017 9:45 am

Jtf wrote:Hi Jim thanks for the input, when you say dropped , does that mean the ac power is shut off & you say to turn off power at breaker on inverter rather than at mate , I thought it’s better to turn off at mate?


Yes, for sure, a Mate command. (BTW, I suppose some use their generator for other things like I do and have the line to the inverter switched or on a remote breaker. That's what I was referring to in the comment. So when welding or running heavy loads, etc. I shut the breaker off so the inverter is out of the circuit. But this wouldn't be necessary if the genset is normally dedicated.)

Jim
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JRHill
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Posts: 291
Joined: Thu Feb 17, 2011 12:12 pm
Location: South central WA
My RE system: -House: FM 80, VFX 3648, FlexnetDC, FlexWare xformer, Mate 3 / Hub, WattPlot/, 2925w SunTech 195, Trojan L16RE-B Batteries. Backup 1: Champion 75531i 3100, backup 2: 11kw Miller Bobcat;
-Well: Grundfos 11-SQF-2 pump, controller & AC switch (CU200, IO101), Morningstar 15a/48vdc Controller, 780w SunTech 195, Trojan golf cart batteries.
-All running since July '11 with no critical problems.


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