Generac 6853 trips truck GFCI

[chl]

It is break before make.

It should be - I didn't test it though and didn't have a schematic at the time I said that.
The schematic indication is break before make so that just leave the coil collapse as the cause of the spike after all.

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[chl]

The spike occurred when switching to OR from the Lightning, if utility power was present.

Did not matter if any loads were enabled in the transfer switch by the breakers, happened when they were all open.

Triple checked all the wiring - no mistakes.

Never heard back from the OP @Hardlanding if his electrician got any word from GENERAC about it.

That would be interesting if anyone at GENERAC in customer service could explain it.

 

[chl]

BTW, I mention all this for the sake of those reading who may not be familiar with the schematic, not because I think you are too lazy to look at the schematic, Chi.

Ha yes, not lazy but sometimes beery eyed, I have to learn to look at schematics when I am wide awake (and have my glasses on) and not at 2am after a long day of shoveling ice and snow, lol.

Now we know it's a DC solenoid.

They should have adding something to suppress the surge current when the coil field collapsed it seems.

 

[ZeusDriver]

after a long day of shoveling ice and snow,

In Oriental NC, a tiny town near the coast, we had 12"! A typical winter is maybe 1" of snow, one time.

 

[chl]

In Oriental NC, a tiny town near the coast, we had 12"! A typical winter is maybe 1" of snow, one time.

Yea, NC got blasted this time.
Here in Northern VA, the problem was the frozen rain that fell after the 5 inches of snow and left a layer of 2 -3 inches of ice on top.

My little snow blower just spun on top of it, and it supported my 150lbs without a crack.

It took me several hours to chop a path 5 feet long to the street wide enough for our Prius to escape.

Probably the worst I've seen up here in my lifetime, and the long cold snap kept everything frozen all week. Yesterday and today we got above freezing and could make some progress.

At least we didn't loose power - of course I was all prepared with the PPOB plugged in and the truck at 90% just in case...ever since I set that up, no outages!

Kind of disappointing, lol.

 

[EVpower]

The issue with the Generac transfer panel has been a thought problem for me since the first post in this thread. Knowing now that the contactor coil is DC operated, suggests that there would be a full wave bridge diode assembly powering the coil. If that is the design, the diodes will supress the voltage spike from the coil.

Maybe try a resistor/capacitor circuit across the switch contacts and see what happens.

Steve

 

[chl]

The issue with the Generac transfer panel has been a thought problem for me since the first post in this thread. Knowing now that the contactor coil is DC operated, suggests that there would be a full wave bridge diode assembly powering the coil. If that is the design, the diodes will supress the voltage spike from the coil.

Maybe try a resistor/capacitor circuit across the switch contacts and see what happens.

Steve

The diodes (there are 2 FWBs connected in parallel with the coil - see the schematic below from a post above) didn't suppress the approx. 10v kick-back surge. I think the FWB puts 12v on the solenoid coil according to an explanation from GENERAC so the surge was probably 12v - I used an analog meter to measure it as it happened and my 10v was an estimate based on where the needle jumped to.

EDIT: It looks to me like the rectifier is getting 240VAC so the coil should be getting 32v DC or so.

There was an approx. 10v kick back voltage spike on either/both GEN Hot wrt to GEN Neutral if UTIL voltage was available when switching.

The only way I can see for the surge to get to the GEN inputs is by arcing in the BBM switches, whether it is the coil collapse or the voltage differences between UTIL and GEN when switching.

To suppress arcing in the BBM switches, then an RC snubber would be a good idea if switching when there is UTIL power applied to the GENERAC or GEN power applied to the GENERAC.


EDIT: Upon further consideration: I guess the MOVs are there to protect the diodes when the coil collapses and produces a kick back voltage of opposite polarity. But it seems they shunt it to the input lines, e.g., E1, E2 and E3?

However, the rocker switch won't work without power from one or the other or both.
Switching manually with the rod supplied would be one way to avoid the arcing and surges.

Seems like GENERAC should have including snubber circuitry in their design.

 

[ZeusDriver]

On looking at the schematic more closely, I've concluded that the things I called variable resistors are actually varistors (like the MOV's used in a surge protector).

I think I am going to cut an access hole in my panel to make it easy to switch manually, and button things up. Maybe at some point in the future, I will modify things to allow the solenoid to operate when using a 120 vac generator.

 

[chl]

On looking at the schematic more closely, I've concluded that the things I called variable resistors are actually varistors (like the MOV's used in a surge protector).

I think I am going to cut an access hole in my panel to make it easy to switch manually, and button things up. Maybe at some point in the future, I will modify things to allow the solenoid to operate when using a 120 vac generator.

Yes, with my glasses on I agree they are the symbol for MOVs, and they seem to be there to suppress surges from the solenoid coil I suppose.

EDIT: I guess they are there to protect the diodes when the coil collapses and produces a kick back voltage of opposite polarity. But it seems they shunt the kick back to the input lines, e.g., E1, E2 and E3?

So then maybe the surges we see on the GEN lines that trip the truck are from arcing of the BBM switches and not from the solenoid coil, eh?

Break before make switches apparently can arc and it seems to be a thing in transfer switches.

Various transients and surges are an issue in transfer switches.

Probably a good idea to add surge suppression at all ins and out of the transfer switch, as the NEMA suggests in their note (pdf attached).

https://www.google.com/url?sa=t&sou...AQFnoECCgQAQ&usg=AOvVaw1OL0BRYoaCqnOpAkhFWWXD

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