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Topic: Transfer switch(es) and inverter (Read 806 times) previous topic - next topic

Transfer switch(es) and inverter

Earlier this week, I turned on our inverter, the second time in a year!  I recently realized that the battery voltage drop under load is OK, and I can make coffee with our new smaller coffee maker!

The outlets were not energized until I opened the bed, saw the bottom transfer switch and tapped it.  Then the inverter-supplied outlets came on.  So I concluded that there is a problem in the Magnetec ATS-100, and if I fully expose it and open it, I might as well replace it.  Since I am in there, I should replace the loudly-humming Esco ES50M as well. 

Two Progressive Dynamics P-52Vs?

So the top transfer switch is for the generator and the bottom one is for the inverter, right?

My big question...  I have Magnum Magna Sine inverter, and the book indicates that it passes through the shore power when off, and inverter power when on.  It all seems to work (when the lower transfer switch activates) but it seems like either the inverter switching or the free-standing Magnetec transfer switch would be redundant.
Matt B
1998 u-320

Re: Transfer switch(es) and inverter

Reply #1 –
In our 2001 the top ATS switches between generator and landline to power the primary panel.  The primary panel feed to the secondary panel goes through the second ATS as does the feed from the inverter to supply power to the secondary panel.

If Generator or Landline power is available the second ATS will feed power from the main panel to the secondary panel.  If these power supplies are not available the second ATS will feed power from the inverter (if it is on) to the secondary panel.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Transfer switch(es) and inverter

Reply #2 –

Matt,

I got rid of both of the ATS boxes on our coach.

Our Magnum MS2812 inverter can "pass through" 50 amps.  It handles the switching duty between shore power and inverter power.  Works great for that purpose.  The swap between power sources is so quick that none of our sensitive electric devices register the change.  I leave our inverter turned on 24/7 because we have a residential fridge.  Our coach is plugged into 50 amp at all times when parked in our driveway.  If we lose grid power in the middle of the night, the inverter instantly comes on and picks up the most important AC load (keeps the beer and frozen pizza cold).

Setting up the inverter for "pass through" to eliminate the ATS may require some reconfiguration of your AC wiring and/or inverter sub panel.

I also eliminated the shore power/generator ATS on our coach to get rid of the annoying humming noise.  Replaced it with a Blue Sea 9093 manual switch.  Simple is good!  See link below:

Transfer switch questions

Amazon.com : AC Rotary Switch - OFF + 2 Positions 240V AC 65A : Boating...




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Re: Transfer switch(es) and inverter

Reply #3 –
My coach also has a eliminated the automatic transfer switches. Shore power wiring and generator both go to a Blue Sea systems manual transfer switch like the one Chuck has.
My inverter is always on. With the solar on the roof it more than keeps up with refrigeration and other loads in the coach. When I had a sticks and bricks I had it plugged into 50 amps always as well. If I wanted the automatic generator switch to work I would have to keep it the generator side of the transfer switch. You wouldn't find a automatic transfer switch in a boat as far as I know anyway. I like the kiss principal. And it opened up a lot of space under the bed where I could put the Hughes auto former and power watch dog.
'99 U320 40 WTFE
Build #5462,
1500 Watts Solar 600 amp Victron lithium
2012 Jeep Grand Cherokee Overland Hemi
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Re: Transfer switch(es) and inverter

Reply #4 –
Quote from: Roger & Susan in Home2 –
In our 2001 the top ATS switches between generator and landline to power the primary panel.  The primary panel feed to the secondary panel goes through the second ATS as does the feed from the inverter to supply power to the secondary panel.

If Generator or Landline power is available the second ATS will feed power from the main panel to the secondary panel.  If these power supplies are not available the second ATS will feed power from the inverter (if it is on) to the secondary panel.
So that makes sense to me.  With an output/no output inverter, the second transfer switch supplies power to the "inverter" breaker box, so it is always on.

With an inverter that always has output, it looks like the second box could be eliminated and the inverter output connected directly to the inverter breaker box.

But if the inverter failed, it would require yanking wires out of stuff and twisting them together (or a manual switch!) to restore power to the outlets supplied by the inverter.

Thanks!
Matt B
1998 u-320

Re: Transfer switch(es) and inverter

Reply #5 –
Many newer inverters have an internal transfer switch so that they can "pass through" the incoming 120v when it is available to a secondary circuit breaker panel.  Your OEM wiring probably only supplies the inverter with 20 amps for charging and the 2400 or so watts provided by the inverter is about 20 amps.  If there is 50 amps available from a landline or generator all of that gets passed to the secondary panel through the second transfer switch.  If you were using the pass through feature it would only be 20 amps.  To pass through 50 amps (iv tour inverter can do that) the AC wiring from the primary panel to the inverter would have to be much bigger as would the wiring from the inverter back to the secondary panel.  And some inverter will pass through that power and add additional amps from the inverter to meet the demand.  That means even bigger wire and circuit breakers.

If you replace the OEM inverter with one that makes 3000 watts that is 25 amps, more than the OEM wiring is designed for.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN
 

SPLIT: Recommendations for Inverter for older coaches [split from Re: Transfer switch(es) and invert

Reply #6 –
Many of the messages of this topic have been moved to Foretravel Tech Talk - https://www.foreforums.com/index.php?topic=43276.0 since they are a discussion separate from the one of this topic.
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2000 U320 36' non-slide / WildEBeest Rescue
2003 U320