I live off grid (limited solar) and am trying to hook up two generators through a Kohler ATS (RXT).

My goal is to use the smaller (8kw) gasoline powered generator on the "utility" side and the larger (20kw) propane generator (Kohler 20RESCL) on the "emergency" side. (all voltage 240v)

I need to do this because I have a finite amount of propane to get me through the winter and there is no delivery (refill) in the winter months to my location.

My thought is with the smaller unit running, the switch would sense this as normal (utility) power, but when I switch it off, the switch would automaticallty sense the loss of power and switch to the backup position. This is where it gets interesting. I do not want to use the auto start functionality of the ATS as I have a relay in place with my inverter (Outback) so the larger unit will start or stop based on preset voltages. This along with using the smaller unit should get me through the season with my propane.

I'm working with an electrician on this be he seems to be having difficulty figuring out how to hook these up to funtion the way I want and need.

Am I missing something in the theory of how an ATS works? Does the Kohler RXT ATS not allow this basic functionality? Do I need a different ATS, if so, suggestions?

As a final note, I've had some issues already with the Kohler (larger) generator so have purchased a separate Generac (7034) designed for off grid use as a backup.

Edit: to clarify this a bit, I'm looking to have the two generators operate through the ATS to supply power to charge the batteries on my Outback system (FX2024T inverters). The output of the Outback system will go directly to the service panel, not through the ATS. To conserve propane, I'm looking to use the gasoline (smaller) generator primarily during the day (manual start/stop) and the larger unit during overnight hours to automatically start/stop the generator (via the inverter) to keep the batteries charged. By my understanding, I should be able to use the ATS at its most basic level (utility or backup power routing only) based on power supplied to the appropriate lugs. Am I incorrect in this understanding? In following up on the statement/question from KH, your statement about sensing the return of power is exactly what I'm looking for. When I turn on the smaller generator (connected to the utility side) the switch should automatically flip to that position from the emergency side. When I switch off the smaller generator, the switch will automatically flip to the emergency side, but not start the generator as this is controlled once the voltage has dropped to a pre-determined level via the inverter start/stop function. At no point would both generators be in operation at the same, but, even if they were, the switch would automatically be to the utility side as that's the default when power utility power is sensed. I hope this helps. Dan

  • You're not clear about what it is you think an ATS does. When the primary source drops out, it switches to secondary source, and as soon as power is available from the primary source again it switches back. You should definitely include a diagram of your system, showing entry points for both generators and your solar array/battery. If your solar array and inverter are grouped with the smaller generator on the main source side of the ATS, once the transfer switch flips, solar power will go to the battery bank and now that the load is disconnected, the battery bank – K H Nov 12 '18 at 0:32
  • plus solar panels will provide enough power for the inverter to output a clean signal, causing the ATS to flip back, but now the load is reconnected to the battery and solar+generator and the inverter drops out again. The ATS just keeps cycling. This is just one example though. A bit more information would be helpful/necessary. – K H Nov 12 '18 at 0:36
  • Since you mention Outback gear, are you using Outback Radians for your inverters perchance? – ThreePhaseEel Nov 12 '18 at 2:31
  • Is upgrading the inverter and battery bank an option here? – ThreePhaseEel Nov 13 '18 at 4:01

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