Radians tripping GFDI ??? Help me understand

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koalamotorsport
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Radians tripping GFDI ??? Help me understand

Post by koalamotorsport » Sat Feb 09, 2019 10:30 am

So this is a new one to me.
Long established system. 5 arrays running through 5 MX60s into two Radian 8048 inverters.
4 of the arrays are 2240W each and share a 4 pole GFDI
The 5th array is 2850W and is on it's own GFDI

I can turn off the 80A input breakers (between the arrays and the MX60s) and the GFDIs trip about 5 seconds after being turned on.

Neither GFDI trips if the Radian's DC breakers are turned off.

They are wired correctly and have been functioning for more than 2 years.
I read this thread http://outbackpower.com/forum/viewtopic ... hilit=gfdi which suggested the panels could be over-rated for the 80A breaker. It is 17F and very sunny right now, although this problem has existed for 3 days now, one of which was a low solar day. However, my MX60s don't even get to finish waking up before the GFDIs trip.

Both GFDIs trip at the same time, even though they are wired completely independently, sharing only the battery connection.

Again, turning off the DC breakers for the Radians fixes the issue. The GFDIs stay on, the MX60s will power up and start charging the batteries with solar.


This doesn't make sense to me. How does turning off the Radians (I tried each one individually, either will trip the GFDIs) remove a short to ground on a different circuit?

Perhaps someone can offer a theory that will point me in the right direction soon. I hate losing this much power at a time of year when I use a ton.
Thanks!
Brett

2 x GS8048
5 x MX60
32 x 280w Chaori modules
10 x 285w GCL modules
Puny 430ah FLA battery bank

2 x Fronius IG Plus Advanced 6.0
48 x 285w GCL modules

10kW propane generator
10kW diesel generator

Kent Osterberg
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Re: Radians tripping GFDI ??? Help me understand

Post by Kent Osterberg » Sat Feb 09, 2019 10:54 am

Brett,

The GFDI breakers are supposed to be the only connection between dc- and ground. Any current flowing from dc- to ground can trip the GFDI breakers; it doesn't have to be associated with a fault in the PV array at all. It doesn't even have to be a dc current. The problem you are having seems like it isn't associated with the PV array. Are there dc loads connected to the system? Are any dc loads shut off by the inverter breakers? Have any loads been added recently? Try turning on the Radian inverters and opening all the ac breakers in the Radian panel.

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Re: Radians tripping GFDI ??? Help me understand

Post by Mike Curran » Sat Feb 09, 2019 11:31 am

Hey Brett - If your Radians are wired externally like my FX's then their negatives are connected together, assuming both connect to your battery. I don't know what goes on inside a Radian, but if there's an internal ground fault on the negative side in either one of them, wouldn't energizing either one of them cause your GFDI to trip?

With all the freeze/thaw cycles we've been having lately and from what you describe I'd be looking at maybe moisture got into one of your Radians. It's a theory, or maybe more like a hypothesis :-k - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

koalamotorsport
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Re: Radians tripping GFDI ??? Help me understand

Post by koalamotorsport » Sat Feb 09, 2019 3:59 pm

Mike Curran wrote:Hey Brett - If your Radians are wired externally like my FX's then their negatives are connected together, assuming both connect to your battery. I don't know what goes on inside a Radian, but if there's an internal ground fault on the negative side in either one of them, wouldn't energizing either one of them cause your GFDI to trip?

With all the freeze/thaw cycles we've been having lately and from what you describe I'd be looking at maybe moisture got into one of your Radians. It's a theory, or maybe more like a hypothesis :-k - Mike
Mike, Both Raidans share a DC- feed (4/0 to a splice block, then 2/0 to each of the 4 negative terminals on the inverters) and both are grounded to the same ground bus bar. I will try disconnecting their grounds tomorrow.

Freeze/thaw should be an issue. All the equipment is inside a heated building, kept at 50F.
Thanks!
Brett

2 x GS8048
5 x MX60
32 x 280w Chaori modules
10 x 285w GCL modules
Puny 430ah FLA battery bank

2 x Fronius IG Plus Advanced 6.0
48 x 285w GCL modules

10kW propane generator
10kW diesel generator

koalamotorsport
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Re: Radians tripping GFDI ??? Help me understand

Post by koalamotorsport » Sat Feb 09, 2019 4:12 pm

Kent Osterberg wrote:Brett,

The GFDI breakers are supposed to be the only connection between dc- and ground. Any current flowing from dc- to ground can trip the GFDI breakers; it doesn't have to be associated with a fault in the PV array at all. It doesn't even have to be a dc current. The problem you are having seems like it isn't associated with the PV array. Are there dc loads connected to the system? Are any dc loads shut off by the inverter breakers? Have any loads been added recently? Try turning on the Radian inverters and opening all the ac breakers in the Radian panel.
Kent,
There have been no physical changes to the system in 7 months. I have recently been messing with the generators, as I cannot get the Radians to bring one of them online. However, that's just been messing with settings, and all settings restored after each test. So no, no changes in the system.
However, to be sure, I opened the generator breaker. No change. Tomorrow I will disconnect the generator grounds.

There are no DC loads, per se, but now that you mention it, there is an A/C Coupled grid tie inverter with two 3420W arrays. That is an A/C connection that would be lost when shutting down the inverters, so that will bear more investigation tomorrow. That inverter has it's own GFDI protection though, and that has not disconnected, so it's a long shot.

Interestingly, late today, when the sun was fading, I was able to get the MX-60s to stay on for a few minutes at a time. That allowed me to check the logs and I saw nothing strange. Voltage never got above 90VDC, so amps should not have gotten anywhere near high enough to trip the 80A breakers in the GDFI. I'm sure I'm looking for a short somewhere.

I neglected to mention in my first post, I disconnected the larger array at the combiner box. It is the only array feeding one of the GFDIs and both still tripped. Tomorrow I will shut down all combiner box breakers in case there is cross feed somewhere outside.

Thanks for the input.
Thanks!
Brett

2 x GS8048
5 x MX60
32 x 280w Chaori modules
10 x 285w GCL modules
Puny 430ah FLA battery bank

2 x Fronius IG Plus Advanced 6.0
48 x 285w GCL modules

10kW propane generator
10kW diesel generator

Kent Osterberg
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Re: Radians tripping GFDI ??? Help me understand

Post by Kent Osterberg » Sat Feb 09, 2019 7:49 pm

It's not surprising that both GFDI's trip, the two sense circuits are parallel to each other- they both connect the DC- bus bar to ground in the GSLC. The sense circuit for the ac coupled PV array is isolated from the Outback GFDI in that the DC- of the ac coupled array is not connected to the GSLC, so it doesn't trip.

The array(s) connected to the combiner that you disconnected isn't the source of the problem. I don't think the other array is either, but you need to disconnect the other combiner(s) to find out. Since the problem occurs when the breaker for either Radian is turned on, you need to determine if the problem is present without ac power going anywhere. Use the Inverter Hot Key to turn off the Radians and see if the GFDI still trips or not.

koalamotorsport
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Re: Radians tripping GFDI ??? Help me understand

Post by koalamotorsport » Sun Feb 10, 2019 11:37 am

Kent Osterberg wrote: The array(s) connected to the combiner that you disconnected isn't the source of the problem. I don't think the other array is either, but you need to disconnect the other combiner(s) to find out. Since the problem occurs when the breaker for either Radian is turned on, you need to determine if the problem is present without ac power going anywhere. Use the Inverter Hot Key to turn off the Radians and see if the GFDI still trips or not.
An estimated 100kw/h of lost production.
Kent, you pointed me in the right direction.

K.I.S.S

First thing I did today was remove the main ground from the ground bus bar in the DC enclosure (I'm not using a GSLC). This isolated the grounds in that box to just the charge controllers and arrays. GFDIs did not trip

I looked at the Mate3 to see if the system would start selling and noticed that a; it was not selling and b; my solar meter bar was maxxed out. Hmmm. Dropped into settings and see the Array Size set to 1000W.

It's funny. Yesterday I was tired and not feeling well. I thought the screen looked different but with the charge controllers off, there was no solar bar, and I assumed them being off changed the way the screen looked. The icons seemed different but I didn't give it much thought at that time. Looking through the owners manual today, it seems the system settings had changed to an off grid format. I had the Generator and Inverter icons instead of the House and $ icons. I have no idea how this happened but I've been messing heavily with settings recently, trying to get the system to bring one of the generators on line. I probably forgot to reset it the last time I messed with it.

In retrospect, I should have scrolled through all the settings to see what I was actually set up for, but instead I simply reloaded the last known configuration from the SD card, which was saved less than a week ago, and bingo, system is fixed.

As is often the case in these situations, it was operator error.

I am, however, really curious as to how a setting in the system can cause a breaker to trip.
Thanks!
Brett

2 x GS8048
5 x MX60
32 x 280w Chaori modules
10 x 285w GCL modules
Puny 430ah FLA battery bank

2 x Fronius IG Plus Advanced 6.0
48 x 285w GCL modules

10kW propane generator
10kW diesel generator

Kent Osterberg
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Re: Radians tripping GFDI ??? Help me understand

Post by Kent Osterberg » Sun Feb 10, 2019 12:41 pm

I am, however, really curious as to how a setting in the system can cause a breaker to trip.
That doesn't seem right. Did you reconnect the ground in the DC enclosure?

koalamotorsport
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Re: Radians tripping GFDI ??? Help me understand

Post by koalamotorsport » Sun Feb 10, 2019 2:10 pm

Kent Osterberg wrote: That doesn't seem right. Did you reconnect the ground in the DC enclosure?
Yes. After the breakers stayed on with the ground disconnected, I reconnected it and they tripped. I did that before I reset the Mate3 configuration.
Thanks!
Brett

2 x GS8048
5 x MX60
32 x 280w Chaori modules
10 x 285w GCL modules
Puny 430ah FLA battery bank

2 x Fronius IG Plus Advanced 6.0
48 x 285w GCL modules

10kW propane generator
10kW diesel generator

Kent Osterberg
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Posts: 1514
Joined: Mon Jun 09, 2003 11:01 pm
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Re: Radians tripping GFDI ??? Help me understand

Post by Kent Osterberg » Sun Feb 10, 2019 2:47 pm

Changing the Mate3 settings shouldn't make any difference.

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Kurt Lundquist
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Re: Radians tripping GFDI ??? Help me understand

Post by Kurt Lundquist » Mon Feb 11, 2019 11:47 am

Brett,

Do you have a CT rated for DC current? Clamp the white wire going to the top of each GFDI (one at a time) and try to capture peak amps before the breaker trips. It takes .5A to trip the ground fault pole of the breaker. Do you have the green wire from each GFDI landed on the same bus bar? Technically you have two negative to ground bonds but the potential to ground should be fairly even if the green wires are the same length and landed close on the same bus bar.

I agree with Kent, your Mate3 settings shouldn't have any impact on the breakers tripping. Also in the Mate3 system info screen you can change screen display type from Backup, Off-Grid, and Grid-Tied. This changes how the front display looks but doesn't have an effect on any of the other system settings. From your description it almost sounds like you might have reset the Mate3 to factory defaults.

-Kurt
Kurt Lundquist
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http://alphaenergy.us/

koalamotorsport
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Re: Radians tripping GFDI ??? Help me understand

Post by koalamotorsport » Mon Feb 11, 2019 12:03 pm

Kurt Lundquist wrote:Brett,

Do you have a CT rated for DC current? Clamp the white wire going to the top of each GFDI (one at a time) and try to capture peak amps before the breaker trips. It takes .5A to trip the ground fault pole of the breaker. Do you have the green wire from each GFDI landed on the same bus bar? Technically you have two negative to ground bonds but the potential to ground should be fairly even if the green wires are the same length and landed close on the same bus bar.

I agree with Kent, your Mate3 settings shouldn't have any impact on the breakers tripping. Also in the Mate3 system info screen you can change screen display type from Backup, Off-Grid, and Grid-Tied. This changes how the front display looks but doesn't have an effect on any of the other system settings. From your description it almost sounds like you might have reset the Mate3 to factory defaults.

-Kurt
Kurt,
My cheap junk Chinese amp clamp failed a while back and I've not replaced it. I should, however, be able to run what amounts to a draw test, with my Fluke DVOM, given the super low amperage.

Both the white and green wires from the GFDIs are factory length, uncut, going to their respective bus bars, but are not side by side on the bus bars. The bus bars are only 3-4 inches long, so they are at least that close. I can't remember exactly, will have to look next time I'm in the power house.

I agree that I likely accidentally reset the Mate3 to default settings instead of restoring from the card, that last time I messed with it. It's the only thing that make sense.

What I can tell you with zero doubt though, is that resetting the mate to my grid tie settings solved the issue. 100%. The problem was a hard fault. Without shutting things down or disconnecting them, the breakers tripped within seconds of reset, EVERY time. The only change to the system as it sits today, selling power, vs Wed -Fri when the breakers were tripped, was the configuration of the Mate3.

If I have time next weekend, I might experiment and let you know what I find.
Thanks!
Brett

2 x GS8048
5 x MX60
32 x 280w Chaori modules
10 x 285w GCL modules
Puny 430ah FLA battery bank

2 x Fronius IG Plus Advanced 6.0
48 x 285w GCL modules

10kW propane generator
10kW diesel generator

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