Tesla tripping AFCI breakers

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Cane811

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Hello all. Not sure if this type of post is even allowed so I apologize in advance. Just trying to poke the minds of people that do this type of stuff every day.

I live in a new construction home with wonderful AFCI breakers. We recently had a 240V/50a breaker and outlet installed in our garage for our Tesla. During the middle of charging the vehicle, we will have three AFCI breakers trip (kitchen lights, garbage disposal, and washing machine). I’ve read nuisance tripping with these, but not so much with a Tesla mobile connector charger.

Does anyone have any feedback on how to mitigate these random trips? It only occurs when charging the vehicle and after about 2-3 hours of charging. It never tripped on the 110 outlet we had before.
 
Some hopefully relevant experience:

The charging circuitry in electric cars can be noisy and generate conducted EMI (if that's the right phrase). My first electric car would scramble the power-line communications between Enphase microinverters and the Enphase Envoy (typically not a problem when charging at night), until I segregated the power lines used by the Enphase with a power line filter. My second electric car sometimes interferes with the power line communications used by Insteon.

So it is quite plausible that the Tesla's charging circuitry is putting out conducted noise that is reaching the AFCI breakers.

Cheers, Wayne
 
wwhitney said:
Some hopefully relevant experience:

The charging circuitry in electric cars can be noisy and generate conducted EMI (if that's the right phrase). My first electric car would scramble the power-line communications between Enphase microinverters and the Enphase Envoy (typically not a problem when charging at night), until I segregated the power lines used by the Enphase with a power line filter. My second electric car sometimes interferes with the power line communications used by Insteon.

So it is quite plausible that the Tesla's charging circuitry is putting out conducted noise that is reaching the AFCI breakers.

Cheers, Wayne
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I appreciate that. I keep banging my head against the wall on what could possibly be doing this. Guess I need to look at the charger. I’ve read on other forums that the Gen 1 mobile connector is a little less “noisy” so I may try to buy one used and just resell it if it doesn’t work out.
 
wwhitney said:
So it is quite plausible that the Tesla's charging circuitry is putting out conducted noise that is reaching the AFCI breakers.
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Would an 1:1 isolation transformer help to reduce the noise? I've read that this is what they are good for, for sensitive electronic equipment, but I've never heard of anyone installing an isolation transformer in combination with an electric vehicle charging station... The project is usually expensive enough as it is without adding in the cost of an additional transformer and the labor to install it.

Could you confirm the existence of noise with an oscilloscope reading?

Also, how would conducted noise register as an arc? Just curious.
 
Cane811 said:
I’ve read on other forums that the Gen 1 mobile connector is a little less “noisy” so I may try to buy one used and just resell it if it doesn’t work out.
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The charger is built into the car and does the actual conversion of AC to DC to charge the batteries. The mobile connector (EVSE) is just a smart AC switch. Changing EVSEs is not going to help at all, the potential issue is whether the charging circuitry in the car has enough filtering.

If it is a conducted noise issue, then it would be solved with more electronic filtering. That could mean a repair to your Tesla (if some of the filtering circuitry in the charger is actually defective, or they just didn't design it with enough), or upgrading your AFCI breakers to the latest version (if they've added more filtering to them), or adding some additional filtering on the EVSE branch circuit. On the last option, I vaguely know that could mean using a ferrite bead (but don't know how to specify or install it) or a separate filtering device (again, not sure how to specify it).

Cheers, Wayne
 
wwhitney said:
The charger is built into the car and does the actual conversion of AC to DC to charge the batteries. The mobile connector (EVSE) is just a smart AC switch. Changing EVSEs is not going to help at all, the potential issue is whether the charging circuitry in the car has enough filtering.

If it is a conducted noise issue, then it would be solved with more electronic filtering. That could mean a repair to your Tesla (if some of the filtering circuitry in the charger is actually defective, or they just didn't design it with enough), or upgrading your AFCI breakers to the latest version (if they've added more filtering to them), or adding some additional filtering on the EVSE branch circuit. On the last option, I vaguely know that could mean using a ferrite bead (but don't know how to specify or install it) or a separate filtering device (again, not sure how to specify it).

Cheers, Wayne
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I’m currently on a quest to find out the results of placing some ferrite cores on some branch circuits that are showing elevated level of arc fault signature for no reason other than LED lighting possibly emanating to much RF/EMF. Once I receive them and give it a whirl I’ll post my results.
 
mopowr steve said:
I’m currently on a quest to find out the results of placing some ferrite cores on some branch circuits that are showing elevated level of arc fault signature for no reason other than LED lighting possibly emanating to much RF/EMF. Once I receive them and give it a whirl I’ll post my results.
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I have heard of that working for appliances on AFCI protected branch circuits.

However, in this case, I expect they would have to be placed on the power supply conductors going to the charger to work.
 
mopowr steve said:
I’m currently on a quest to find out the results of placing some ferrite cores on some branch circuits that are showing elevated level of arc fault signature for no reason other than LED lighting possibly emanating to much RF/EMF. Once I receive them and give it a whirl I’ll post my results.
Click to expand...
I assume that you're going to put all circuit conductors (e.g, L-N or L-L) through a ferrite core in order to increase the impedance to common-mode interfering signals and thereby reduce the amount of conducted interference. It'll be interesting to hear what your results are. Be sure to select a ferrite core material that has a high enough permeability to provide filtering below 1 MHz, and preferably below 100 KHz.

If the interference is primarily differential-mode (i.e., current flowing in opposite directions through L-N or L-L like 60Hz current does) then the common-mode choke configuration will not be effective. To help attenuate differential-mode interference you'd have to put a choke on each conductor, which would also attenuate any common-mode that's present. However, it's possible the core could then saturate and be ineffective with a sufficiently high 60Hz AC current because the 60Hz magnetic fields of the conductors will not be cancelling in the core (depending on the type and construction of the core).

If you determine that ferrite cores are effective, then they should really be placed near the load that's the source of the interference instead of inside the panel (even though that may require more cores). If placed in the panel on the home run conductors then they will also attenuate the spectral "noise" that the AFCI uses to determine whether an arc fault is occuring, and therefore potentially reduce the AFCI's sensitivity to an actual arc fault.
 
synchro said:
I assume that you're going to put all circuit conductors (e.g, L-N or L-L) through a ferrite core in order to increase the impedance to common-mode interfering signals and thereby reduce the amount of conducted interference. It'll be interesting to hear what your results are. Be sure to select a ferrite core material that has a high enough permeability to provide filtering below 1 MHz, and preferably below 100 KHz.

If the interference is primarily differential-mode (i.e., current flowing in opposite directions through L-N or L-L like 60Hz current does) then the common-mode choke configuration will not be effective. To help attenuate differential-mode interference you'd have to put a choke on each conductor, which would also attenuate any common-mode that's present. However, it's possible the core could then saturate and be ineffective with a sufficiently high 60Hz AC current because the 60Hz magnetic fields of the conductors will not be cancelling in the core (depending on the type and construction of the core).

If you determine that ferrite cores are effective, then they should really be placed near the load that's the source of the interference instead of inside the panel (even though that may require more cores). If placed in the panel on the home run conductors then they will also attenuate the spectral "noise" that the AFCI uses to determine whether an arc fault is occuring, and therefore potentially reduce the AFCI's sensitivity to an actual arc fault.
Click to expand...
Maybe I should just put the ferrite cores over the L,N wires directly coming from the LED trims. Should be real easy that way.
 
mopowr steve said:
I’m currently on a quest to find out the results of placing some ferrite cores on some branch circuits that are showing elevated level of arc fault signature for no reason other than LED lighting possibly emanating to much RF/EMF. Once I receive them and give it a whirl I’ll post my results.
Click to expand...
Great thread.
My first response to customer complaints of AFCI tripping is to have them 'Duck Duck Go' the term "AFCI nuisance tripping".
Is there a fast way to show the customer an elevated level of arc fault signature in their home or business?
Thanks.
 
Ravenvalor said:
Great thread.
My first response to customer complaints of AFCI tripping is to have them 'Duck Duck Go' the term "AFCI nuisance tripping".
Is there a fast way to show the customer an elevated level of arc fault signature in their home or business?
Thanks.
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Well, maybe.
I have the Siemens Intelliarc Arc Fault Diagnostic tool which has a transmitter that wires in line with the arc fault breaker and transmits to a handheld level meter that shows the severity of arc fault signature, amperage and ground fault level.
Now with that being said, I got this before LED lights really hit the market, so now I don’t know if the noise or RF created by LED lights is actually being picked up by the transmitter through the line or if the RF is messing with the signal from the transmitter and handheld meter.
It’s a shame we need an electronics engineer with doctorate on payroll to troubleshoot this bullish.t
 
tesi1 said:
WOULD IT BE EASIER TO INSTALL A TVSS WITH SEINWAVE TRACKING & OR FILTERING AT YOUR LOADCENTER
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I do have a TVSS installed but as far as saying “with sine wave tracking and/or filtering” what product have you seen with said features?
 
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