Classic Arc Fault ~ What Else to Check?

[Matrix]

I have tried to read everything I can find on Diagnosing Arc Faults.

I have 2 Classic 150s
- One is about 6 years old
- One is about 2 years old

The Older one has been throwing Arc Faults randomly (but seldomly) since 2021.  Back in 2021 I posted for help about an AC Chop Saw that seemed to be setting it off.  After checking connections, I adjusted both the Time and Sensitivity.  It took setting them to max to get the Classic to stop nuisance tripping. Thought I had it licked.

But In the past few days it has started up again.  Even with Time and Sensitivity all way up.

I have checked connections again.  My New 2nd Classic is not triggering the Arc Fault and is set to factory defaults for Arc Fault.  So ...
- After checking all DC connections
- I completely reversed  which classic took which Array.  Reversed all wiring from array down thru combiner and into the classics at the E-Panel Solar In DC Busbar.
- I connected the + & - coming into the MN E-Panel from my New East array and connected it to my old classic, and did the same with the Older West array to my new classic

My thought was ... if there is an Arc on that array or its combiner, fuses, breakers or wiring somewhere ... it should now trip the Arc Fault on the new Classic and the Old Classic should stop faulting.

Not so ... The old Classic continues to Arc Fault,  the New Classic with the older array now connected to it does not trigger an Arc Fault.  Shouldn't reversing the Arrays have caused the Arc Fault to now be tripped in the New Classic and not the Old Classic?

Where else can i look?   The only thing that is unchanged is the Breakers from inside the E-Panel to and from the classic and the 2 ft of wire between the Classic and it's breakers.  What else could it be?
- With the Arrays reversed that should have caused the Arc Fault to be triggered in the other classic if it was in the Array, combiner or wiring down from the roof correct?
- There is no visible sign of Arcing in the E-panel at any of the connections there.
- Could it be inside either the MN Solar 80amp or 60 amp breaker?
- Could it be inside the Classic itself? 

Guess I need to pull apart the classic itself and check the connections.
- but could it be on the Circuit board of the Classic?
- Or in the internal factory wiring?
- What else can I do?

I have tired Full Time and Sensitivity turned to max.  It still trips.  The only thing that seems to stop it is to set the Mode from 1 to 0 ... but I'm sure this is NOT a good idea

At what point in this testing would you say it is safe to operate without Arc Fault?

Ideas? 

Thanks
Mike

[ClassicCrazy]

I have always left arc fault disabled on my Classics and never had any issues.
Larry

[Matrix]

I have always left arc fault disabled on my Classics and never had any issues.
Larry

Thx Larry. I'm at that point myself

[FNG]

So the Classic has a couple revisions of Arc Fault detection, sounds like you have both. As we rolled out the Hawkes Bay and Barcelona we also had to introduce a new Arc Fault processor, and the code is much better at ignoring false positives like motors etc that are noisy.

As a side note the Classic listens to the complete system it has no way to filter one array from the other for example. And some battery based inverters are worse at passing AC noise through to the DC side as well. I am guessing you have an AC load somewhere causing this and barring finding/fixing that turning off AF in the older classic may be the way to go, The new classic will still detect AF