Is AFCI+GFCI breaker tripping in main panel inevitable when using a Reliance Controls Manual Transfer Switch?

[aunsafe2015]

I've read a bit about people getting C/AFCI+GFCI breaker trips in their main panel when they are using a Reliance Controls manual transfer switch (MTS). I understand that this has something to do with neutral switching and/or neutral+ground bonding issues. Apparently the main panel breakers trip when switching the circuit from LINE to GEN (or maybe from GEN to LINE) on the MST.

Does anybody know if using a Tier 1 quality inverter (e.g., Victron or Sol-Ark) would eliminate these C/AFCI+GFCI breaker trips?

Or are C/AFCI+GFCI breaker trips in the main panel inevitable when using a Reliance Controls MST?

Thanks for any input. I'm in the middle stages of figuring out a battery backup system and debating between a Reliance Controls MST versus an interlock kit. The advantage of the MST would be that I could leave the breakers in GEN mode with the inverter in pass-through mode to have it operate as an automatic transfer switch / UPS at times. The benefit of the interlock kit would be access to every breaker in the panel and not having to worry about the neutral switching/bonding issues.

 

[RCinFLA]

GFCI's in main panel should not be affected by inverter with the exception of inverter AC input branch, which should not have a GFCI breaker in inverter AC input path since EMI filter capacitors in inverter may create a small amount of leakage current to inverter case ground that will trip a GFCI.

AFCI's are affected by EMI emissions, a.k.a. arcing or digital switching emissions from inverter. Only thing you can do is to reduce the arcing or digital noise is by installing a line filter on the inverter's AC input line.

Any immediate A/B transfer between two non-synchronized AC sources can trip an AFCI breaker. You should never do an immediate inverter input A/B AC transfer between two unsynchronized AC sources, like grid and generator AC sources. The inverter must first release its AC input pass-through relay before another AC source is applied to inverter AC input. This can take a few seconds to a minute after inverter AC input is removed.

If there is an AC motor running on inverter or transfer switch AC output, an immediate A/B AC transfer of unsynchronous AC sources can cause AC motor to kick back a large surge current.

 

[aunsafe2015]

GFCI's in main panel should not be affected by inverter with the exception of inverter AC input branch, which should not have a GFCI breaker in inverter AC input path since EMI filter capacitors in inverter may create a small amount of leakage current to inverter case ground that will trip a GFCI.

AFCI's are affected by EMI emissions, a.k.a. arcing or digital switching emissions from inverter. Only thing you can do is to reduce the arcing or digital noise is by installing a line filter on the inverter's AC input line.

Any immediate A/B transfer between two non-synchronized AC sources can trip an AFCI breaker. You should never do an immediate inverter input A/B AC transfer between two unsynchronized AC sources, like grid and generator AC sources. The inverter must first release its AC input pass-through relay before another AC source is applied to inverter AC input. This can take a few seconds to a minute after inverter AC input is removed.

If there is an AC motor running on inverter or transfer switch AC output, an immediate A/B AC transfer of unsynchronous AC sources can cause AC motor to kick back a large surge current.

Thanks for the input. I think your paragraph about "immediate A/B transfer between two non-synchronized AC sources" is may be the part that would be relevant to my concern. Would that apply if you are outputting from the inverter to a transfer switch using pass-through mode from the grid, and then a grid outage occurs, causing immediate switch from grid power to battery power? Is that an "immediate inverter input A/B AC transfer between two unsynchronized AC sources" that might cause an AFCI trip in the main panel?

I don't have a deep understanding of it but I've read more than one post about AFCI tripping due to an issue with neutral switching and/or neutral-ground bonding. Apparently it has something to do with the fact that, since the Reliance MSTs do not switch neutral, that changing the Reliance MST from LINE to GEN (or maybe it is GEN to LINE) does something that causes AFCIs in the main panel to trip. I've read about it happening both with Delta Pro and its built in inverter, and with Growatt inverters. I'm curious if a higher-end inverter like Victron would have the same issue or if it handles neutral switching differently such that the AFCI trip would not be expected to occur.

 

[ChrisG]

@aunsafe2015
You are absolutely right about GFCI AFCI breakers in the main panel with a reliance transfer switch. Can confirm myself. Has nothing to do with the inverter. There was a thread about this a while ago where someone mentioned getting this to work but seemed like the juice wasn’t worth the squeeze.

I just leave the circuits on GEN all the time which is actually fed by the inverter. Only switch back to LINE and reset the main GFCI and AFCI when I do inverter maintenance.

 

[aunsafe2015]

@aunsafe2015
You are absolutely right about GFCI AFCI breakers in the main panel with a reliance transfer switch. Can confirm myself. Has nothing to do with the inverter. There was a thread about this a while ago where someone mentioned getting this to work but seemed like the juice wasn’t worth the squeeze.

I just leave the circuits on GEN all the time which is actually fed by the inverter. Only switch back to LINE and reset the main GFCI and AFCI when I do inverter maintenance.

Thanks for the input. My plan was to do the same thing -- leave the circuits on GEN all the time. So when exactly is it that you get the trips? Only when you are switching between LINE and GEN?

Also, I haven't seen much discussion of the Reliance Controls Neutral Kit (https://www.reliancecontrols.com/products/reliance-controls-pro-tran-2-neutral-kit-6-circuits-nk06-1) on this forum (or anywhere else for that matter). Is it recommended to install that? Or do you just forgo AFCI/GFCI protection at the breaker level when running in GEN mode?

 

[ChrisG]

I just ignore when in GEN. The second I switch from LINE to GEN it trips. I haven’t looked into the other one you linked. Now I don’t recall if an actual floating neutral gas generator has the same trip. I need to try it this weekend.

 

[aunsafe2015]

I just ignore when in GEN. The second I switch from LINE to GEN it trips. I haven’t looked into the other one you linked. Now I don’t recall if an actual floating neutral gas generator has the same trip. I need to try it this weekend.

If you try it, please report back.

 

[RCinFLA]

I would never recommend anyone use an immediate A/B AC automatic transfer switcher that does not have a dead timer gap during change over.

In the worst case you can damage inverter when jumping from a generator to AC grid when the two AC sources happen to be 180 degrees out of phase when the immediate switchover is made. The inverter input is being subjected to effectively twice the AC input voltage due to the two sources being out of phase. If you are lucky, it just pops the breaker or shuts down the inverter due to overload.

For automatic A/B transfer on AC output of inverter and grid, it can damage loads like refrigerator or air conditioner compressors.

 

[ChrisG]

I would never recommend anyone use an immediate A/B AC automatic transfer switcher that does not have a dead timer gap during change over.

In the worst case you can damage inverter when jumping from a generator to AC grid when the two AC sources happen to be 180 degrees out of phase when the immediate switchover is made. The inverter input is being subjected to effectively twice the AC input voltage due to the two sources being out of phase. If you are lucky, it just pops the breaker or shuts down the inverter due to overload.

For automatic A/B transfer on AC output of inverter and grid, it can damage loads like refrigerator or air conditioner compressors.

That’s why I leave it on Gen all the time.

 

[Hedges]

I presume input of inverter is not being switched. Grid-interactive inverters need a dead time to shut off before reconnecting to an out of phase source.

Reliance switches single or split phase "hot" wires of circuits. It does not switch neutral. Therefore, if switching a circuit connected to GFCI I would expect GFCI to trip due to line/neutral imbalance.

I think it could be possible to use a split-phase Reliance switch (DPDT + breaker) to switch line and neutral of a single-phase GFCI circuit, by reassigning half the switch to neutral. Probably unapproved unlisted undocumented, but you're in the company of DIY hackers here.

I don't have a deep understanding of it but I've read more than one post about AFCI tripping due to an issue with neutral switching and/or neutral-ground bonding. Apparently it has something to do with the fact that, since the Reliance MSTs do not switch neutral, that changing the Reliance MST from LINE to GEN (or maybe it is GEN to LINE) does something that causes AFCIs in the main panel to trip.

I agree.

I've read about it happening both with Delta Pro and its built in inverter, and with Growatt inverters. I'm curious if a higher-end inverter like Victron would have the same issue or if it handles neutral switching differently such that the AFCI trip would not be expected to occur.

Inverter can't have an impact on that, when Reliance switches individual circuits between a breaker in main pane and a breaker in Reliance. Well, AFCI may be a different sort, but GFCI measures imbalance, so both line and neutral must be switched.

As for AFCI, it detects spectrum signature of arcing. I suppose brief arcing in a switch doesn't trip it, while motors might.

For automatic A/B transfer on AC output of inverter and grid, it can damage loads like refrigerator or air conditioner compressors.

So I hear but not sure I believe. Out of phase is just a slight jerk, nothing like locked rotor amps from a standstill.
Simply turning a motor off then back on while still spinning could also land at 180 degrees out of phase. I'm sure you've experienced that is no big deal.
Coming to a stop then restarting before pressure unloader, that I could see being a severe overload.

I should test this out - make a crossover switch and try 180 degree out of phase power, monitoring with a scope.
My only concern is ensuring arc isn't formed that shorts power to ground or L1 to L2 (which I've done with DPDT relays.)

 

[RCinFLA]

So I hear but not sure I believe. Out of phase is just a slight jerk, nothing like locked rotor amps from a standstill.

It is a lot more than LRA current. A large motor can kick back a large surge current that can damage inverter.

A motor's nameplate LRA number is spec'd at minimum rated run voltage. Actual LRA is usually greater than nameplate, depending on AC voltage applied. The reason it is spec'd this way is to ensure a branch circuit short period max breaker current does not exceed the low end LRA current of motor.

 

[Hedges]

Of course you can cut power to a motor while it is running, or stalled.

What happens if you cut power to a motor, then turn it back on before it comes to a full stop?
As it is slowing down, it will pass through in-phase and 180 degrees out of phase many times.

Is it different with off-grid inverter rather than generator or grid?
Are some inverter architectures able to handle loads in all four quadrants, and others not?

I suppose some motors do braking into electrical short, vs. open circuit. I've notice my electric lawn mower slows to a stop rapidly when switch is released, but keeps spinning longer when power cord is unplugged. The switch must short motor windings when released. Probably a universal motor? Some residual magnetism excites it and then it self-excites?