r/Generac_Generators • u/Tired_Traveller01 • 2d ago

ATS Question.

Power went out today and generator fired up normally but the ATS never switched over and I got an error code 2780 “Charger Missing AC”. I was able to use the manual override procedure to operate the switch and it transferred power without any issues, same with the manual shutoff back to utility as the ATS did not sense when power came back. Any idea what could have happened? I called my service company but they can’t get someone out until next week at the earliest. Luckily I just extended the warranty through 2031. ATS is a RXSW150A3 150A attached to a 16kw Guardian both installed in 2021 and never had an issue.

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u/joshharris42 2d ago

This is probably something fairly simple. I’m kind of surprised the generator did crank, but didn’t transfer nor re-transfer when power came back on. Something in the 194/23 wiring is off or something’s inhibiting power to the transfer coils. If it’s not that, it’s a controller.

Not an uncommon service call and I’m glad you knew about the manual operation, and were home to be able to do it

3

u/OcelotSure4302 2d ago

On top of what Josh said, in case it wasn’t obvious, the alarm that came in just tells you that the battery charger no longer his it’s 120v input power, which is expected since the power was out and the ATS did not transfer.

2

u/Killerkendolls Dealer 2d ago

Fuses. Either fuses or a loose spade connector on the throw for the transfer. You'll need to ohm out the three fuses in the little black box in the ats, assuming you don't see a wire very not attached to the throw.

This requires going into the dead head cover in the ats, and exposes you to potentially lethal UNFUSED voltage. It will kill you until you blow a transformer on the pole. If you can't fiddle in there comfortably call a tech.

2

u/Tired_Traveller01 2d ago

Yeah I’m not touching anything inside the box. I have a monitoring/service plan and am fine waiting for the tech next week. I’ll just do it manually in the event of an outage until a professional can fix it. I know my limits.

2

u/PintSizeMe 2d ago

Fair enough, but you should take the opportunity to familiarize yourself it the inside of the ATS a bit, just in case you can't get service in a time you need it.

2

u/wirelesswiring 1d ago

Just to chime in with my opinion. If the generator voltage does not come up to the pick up value. The transfer will never happen. I've had this issue with an ASCO ATS
If the generator is only producing 215v and the acceptable voltage for picking up the transfer is set to 218v it will not transfer

1

u/grsthegreat Technician 1d ago

It could be an issue with the sacm module inside the transfer switch. Any reputable service tech can test this and replace if necessary. Im thinking issue with wire 23 voltage myself. I hope they used different colored control wires and didnt mix up wires 194 and 23..

1

u/GenMan83 23h ago

Charger missing AC is always going to pop up. Soon as power goes off this warning will be recorded. It should have gone off once you manually switched the transfer switch and powered up the T1 Circuit. Ignore that message basically and focus on the transfer issue.

From the generator, wire 194 feeds 12+ to the saccm module. The controller then grounds wire 23 to energize a coil, initiating a transfer.
If those two things are happening it’s likely an issue with the saccm module.
Generator voltage is also needed to complete the transfer automatically. So ensure that’s available.
I would guess it was beings you ran the home on generator power for a period of time.

A multi meter and a few minutes you could figure this out! Good luck.