Bypass 600v Ground Fault fuse

Discussion about the FM100 AFCI Charge Controller
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Tworude
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Bypass 600v Ground Fault fuse

Post by Tworude »

I'm 80 miles from the nearest road and the fuse in the fm100 AFCI is gone. I don't get another helicopter in here for 2-3 weeks. I'm totally off grid, is there a way to temporarily bypass the fuse until the helicopter gets here without risking my equipment?
raysun
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Re: Bypass 600v Ground Fault fuse

Post by raysun »

By "gone" does that mean the fuse is missing, or that it has opened? If the latter, there was most likely a predicate event that caused it to "blow". It would be important to understand the events leading up to the controller being deactivated.
fcwlp
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Re: Bypass 600v Ground Fault fuse

Post by fcwlp »

The FM100 AFCI has both Ground Fault and Arc Fault protection. Both of these NEC required features are to protect a structure from burning down versus personnel protection. So if the array is on a structure, you want to be careful given your remote location. The fuse is for the Ground Fault portion of the protection.

Most likely the issue is with an array wire that has been cut and grounded to module frame or other grounded structure.

Below is an old document that gives some troubleshooting advice on tracking down ground fault issues.
GFDI Ground Fault Troubleshooting.pdf
(151.15 KiB) Downloaded 59 times
You will have to make some adjustments to the measurement positions as the negative of the PV array in the FM100 AFCI goes to the terminals in the FM100 versus the DC Negative bus bar. This is shown in the file below on page 12 (I had to delete a few pages to meet size limitation.)
FM100 AFCI Wiring Webinar (pages removed).pdf
(1.43 MiB) Downloaded 52 times
Only after you find and fix the ground fault, can you consider a MacGyver solution. The GFDI fuse is 0.75A. Wire sizes in the 30-32 AWG range have approximately the same current rating, see below for details. Good source would be the wires from an old flexible battery cable. Solder to each terminal of the fuse or carefully wrap around each side of the fuse holder, with the PV disconnected.
https://www.powerstream.com/Wire_Size.htm

For a few laughs, do not go with one of the following options.
Guide to Fuse Replacement.jpg
raysun
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Re: Bypass 600v Ground Fault fuse

Post by raysun »

:grin:

I've seen that 2000A slo-blow fuse in action.

Also I was told a shiny copper penny was rated at 93AAC. Not sure about DC, or the zinc alloy fuses.
Tworude
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Re: Bypass 600v Ground Fault fuse

Post by Tworude »

I do have nails, wrenches and bullets! The fuse is missing. Just put in a new FM100. The array is on a pole 100 feet away. I sure would like to use my solar system while I wait for the helicopter. I really appreciate the help
raysun
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REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Bypass 600v Ground Fault fuse

Post by raysun »

The fuse is literally missing?

There's some QC for you.

I guess the 30ga wire McGuyver approach would be the best of a bad situation.

I've never seen the fuse in question. Is it possible it worked loose and fell into the chassis somehow?
Tworude
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FN-DC FLEXnet DC
2 Fortress EFlex 5.4 Lithium
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Re: Bypass 600v Ground Fault fuse

Post by Tworude »

There is a possibility that someone will pick one up in town tomorrow and do an air drop on Wednesday. If I'm sure that I won't hurt the equipment I'll put in a temporary bridge. Breakup is a tough time, 5-6 weeks of isolation except for helicopters.
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Re: Bypass 600v Ground Fault fuse

Post by sbrownian »

Out of Trebuchet range, eh?
Information, you get not; if incorrect question, you ask..
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Re: Bypass 600v Ground Fault fuse

Post by JRHill »

sbrownian wrote: Mon Apr 19, 2021 3:44 pm Out of Trebuchet range, eh?
Gosh that's funny and memories. My 2nd son was at Pacific Lutheran U finishing a Mech Eng program. The team built a Trebuchet for their senior project. And for those that remember, with the pictures and arrows and diagrams from Arlo Guthrie days, plus all the calculations of range. They had to make arrangements with campus security to work with it. City police got involved too. I recall that the biggest PITB was to fix the divots in the soccer field. I believe the unit is in their museum of crazy things students have done. He later went on to get a BS in Physics and MS in SW eng from Columbia.

Trebuchets are cool devices. But they don't work well in trees.
GBelau
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Re: Bypass 600v Ground Fault fuse

Post by GBelau »

Contributing an idea:
FM100 ground fault detection fuse, from Outback data, 0.75 A 600 V
Also form Outback data, arc fault protection does not have a fuse, it is a dual algorithm detection system, not a fuse.
Hence it must be the ground fault detection fuse that is missing?
In a pinch can use a wire:
From: Reference: American Wire Gauge - http://en.wikipedia.org/wiki/American_wire_gauge
#28 AWG has 0.83 A Ampacity @ 60°C
Where to get a #28 AWG wire while out in the bush? Check bigger cables/wires on hand and count the strands, check on reference for Stranding Charts to find something that might work.–
https://www.iewc.com/userfiles/assets/t ... charts.pdf
Note, if have a ground fault it would probably be more than the 0.75 A when a ground fault happens. This leaves some room in regards to designing a temporary McGiver wire fuse depending on how fast one wants the wire/fuse to melt.
All such is at your own risk obviously – I am a school graduate engineer, not a P.Eng, with 5 years solar design and installation experience, including off-grid, and am a NABCEP certified PV Installation Professional. My interest in wires-for-fuses is from a magazine article where someone wrote about such a fix while stuck far from a store.
Hope this may be of help.
GBelau
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Re: Bypass 600v Ground Fault fuse

Post by GBelau »

Sorry, just noticed the thread was from April 2021, I had read August 2021, and thinking it recent, replied. Obviously a solution would have been found already
fcwlp
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
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Re: Bypass 600v Ground Fault fuse

Post by fcwlp »

GBelau wrote: Fri Aug 27, 2021 12:45 pm In a pinch can use a wire:
From: Reference: American Wire Gauge - http://en.wikipedia.org/wiki/American_wire_gauge
#28 AWG has 0.83 A Ampacity @ 60°C
Where to get a #28 AWG wire while out in the bush?
Welcome to the forum. We had the same idea, although I recommended 30-32 AWG.
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