VFXR 3024 pops grid RCD after a while

Discussion about adding energy storage to grid-dependent inverters using OutBack Power technology
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Echo5
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My RE system: FLEXmax 80, VFXR 3024, MATE3s, HUB10, FLEXnet DC, 2x150Ah Sterling LiFePO4 24V batteries, 8x220w panels in 4 strings of 2.

VFXR 3024 pops grid RCD after a while

Post by Echo5 »

Hi All

I have a VFXR 3024 which keeps popping an RCD on the main electricity panel after about 2 minutes of pulling power from the grid. Everything else carries on working correctly. I am attempting to get the inverter to charge the batteries in Mini-Grid mode.

The inverter is part of a FlexPowerOne system (so I assume its wired correctly internally) and there are no other external components. If the incoming grid connection has it's ground wire connected inside the inverter, the RCD pops immediately as soon as the grid is connected. Disconnecting the ground wire, the inverter will happily charge for about 1-2 minutes then pop the RCD. The RCD is 30mA - would a less touchy higher rated one be advisable? The inverter charge current is set low at 2Amp.

Any advice appreciated.
raysun
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Re: VFXR 3024 pops grid RCD after a while

Post by raysun »

One consideration is the Residual Current Device is doing what it's designed to do.
If the incoming grid connection has it's ground wire connected inside the inverter, the RCD pops immediately as soon as the grid is connected.
I'd take this as a fairly large red flag. Either there is a ground fault in the wiring, or the RCD may be defective.
The inverter is part of a FlexPowerOne system (so I assume its wired correctly internally)
One would hope so, but shouldn't bet one's life on it. A walk-through of the internal wiring is a bit of a hassle, but necessary, IMO.
fcwlp
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Re: VFXR 3024 pops grid RCD after a while

Post by fcwlp »

The FlexPowerOne comes with the Neutral bonded to the Ground. Remove the N-G bond and test.
raysun
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Posts: 10766
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: VFXR 3024 pops grid RCD after a while

Post by raysun »

VFXR3024 is mentioned. Is this the "-E" model?
Screenshot_20231001_124229_Drive.jpg
FlexPower One - Grid Tied circuit diagram

Download version here: https://www.outbackpower.com/downloads/ ... id_tie.pdf
Echo5
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My RE system: FLEXmax 80, VFXR 3024, MATE3s, HUB10, FLEXnet DC, 2x150Ah Sterling LiFePO4 24V batteries, 8x220w panels in 4 strings of 2.

Re: VFXR 3024 pops grid RCD after a while

Post by Echo5 »

Thank you both for the advice!
fcwlp:> The FlexPowerOne comes with the Neutral bonded to the Ground. Remove the N-G bond and test.
Yes, as raysun suggested, I did have a look at the internal wiring and there is a very obvious, rather largish, green and yellow ground wire running from the ground bus bar up to the neutral bus bar inside the VXFR3024. My experience at these things is not extensive but it does seem odd to tie these two together. What would be the purpose of this and why it would be done?
raysun:> VFXR3024 is mentioned. Is this the "-E" model?
Yes it is. Clearly labeled VFXR3024E on the side of the device. What is the significance of this model version? Thank you for the circuit diagram - if I am interpreting it correctly there is no connection between the ground and neutral in it (as fcwlp suggested above).
fcwlp
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My RE system: GS8048A, FM80 w/3,600W PV Fixed, FM80 w/2,700W on Zomeworks tracker, Mate3, 24 Trojan 2V L16 1100AH @ C20, Grid-Tied with Kohler 14RESA LPG Generator and MEP-803 Diesel if needed.

I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: VFXR 3024 pops grid RCD after a while

Post by fcwlp »

Echo5 wrote: Mon Oct 02, 2023 4:15 am Yes, as raysun suggested, I did have a look at the internal wiring and there is a very obvious, rather largish, green and yellow ground wire running from the ground bus bar up to the neutral bus bar inside the VXFR3024. My experience at these things is not extensive but it does seem odd to tie these two together. What would be the purpose of this and why it would be done?
That is the N-G bond to remove. The N-G bond needs to occur in only one location, otherwise there can be current flowing in the ground loop created which is likely tripping your RCD. In the US the electrical code has this bond made just after the power enters the meter. In the US a RCD is not used on the incoming power but rather GFIs are used at the outlets or circuits supplying the outlets.
Echo5
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My RE system: FLEXmax 80, VFXR 3024, MATE3s, HUB10, FLEXnet DC, 2x150Ah Sterling LiFePO4 24V batteries, 8x220w panels in 4 strings of 2.

Re: VFXR 3024 pops grid RCD after a while

Post by Echo5 »

SUCCESS

Removing the wire linking the ground and the neutral busses in the inverter appears to have fixed the issue. The inverter has been running in Mini-Grid for several hours now with no problems. The system rarely got more 2 minutes before.

Thank you all for your help. It is much appreciated.
fcwlp
Forum Emperor
Posts: 1276
Joined: Wed Jan 22, 2020 9:40 am
My RE system: GS8048A, FM80 w/3,600W PV Fixed, FM80 w/2,700W on Zomeworks tracker, Mate3, 24 Trojan 2V L16 1100AH @ C20, Grid-Tied with Kohler 14RESA LPG Generator and MEP-803 Diesel if needed.

I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: VFXR 3024 pops grid RCD after a while

Post by fcwlp »

Echo5 wrote: Tue Oct 03, 2023 8:30 am SUCCESS

Removing the wire linking the ground and the neutral busses in the inverter appears to have fixed the issue. The inverter has been running in Mini-Grid for several hours now with no problems. The system rarely got more 2 minutes before.

Thank you all for your help. It is much appreciated.
Congrats
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