Shore power and generator

[Muggs]

Ours will always go to generator if started. When I exercise gen, I kill breaker to shore power, then start and load with A/C. Always run for 30 to 45 minutes minimum when gen door open. Later versions of my unit have vent installed in door.

ATS connections get checked every 6 to 9 months.

[Beau388]

Originally Posted by Wiley1

I absolutely understand what an ATS does. In the Navy we called it an ABT: automatic bus transfer. You can only have one source of AC power to your distribution panel. Having them both connected at the same time would be a disaster for a whole slew of reasons. In addition to being a safety device, it is also a convenience device. Because it is automatic, the user doesn't have to know when to pull down on a big switch handle.

My question is about priority. When both sources of power are available, why would the ATS choose to give priority to the generator over shore power? That seems backward to me and, so far, nobody here has been able to explain the reasoning for it.

If you have a Generac system at your house, which do you think is given priority? The utility power or the generator power? To me, an RV should be no different.

I would assume it is due to the complication of shutting down the generator before restoring shore power.

[taylorbob1]

Here's the Thor 30amp instruction manual.
They (along with other ATS manufacturers) talk about Generator delay to stabilize voltage.

https://manuals.solidsignal.com/Manual_for_THTS-30.pdf

[Scubawise]

Originally Posted by taylorbob1

Interesting thought.
Now you have me wondering…

Now we just need to figure out why RV manufacturers wire it with genny superior and plug-in inferior.

Because if power goes out..cpap dogs etc ok

[Pete'sMH]

I like it the way it comes but if you want it the other way why couldn’t you just reverse the shore and generator connections in the ATS? 10 - 15 minutes of easy work. How would the ATS know the difference? Both are 120V AC. Just sayin…

[Wiley1]

Originally Posted by Pete'sMH

I like it the way it comes but if you want it the other way why couldn’t you just reverse the shore and generator connections in the ATS? 10 - 15 minutes of easy work. How would the ATS know the difference? Both are 120V AC. Just sayin…

Of course I could do that. I was an electrician in a previous life.

But, before I pull out a screwdriver to redesign something that has been around for 40 years, I thought I'd try to understand the reasoning behind the original design. So far, nobody seems to know for sure.

[Jimbo56]

Originally Posted by Jeg

When I run the AC on generator power in my Thor ACE, everything is fine for about 30 min. or less, then the generator just quits running...so I start it back up and same thing again...any ideas where I might begin to troubleshoot the problem..?

Low oil?

[Jimbo56]

Originally Posted by Wiley1

Of course I could do that. I was an electrician in a previous life.

But, before I pull out a screwdriver to redesign something that has been around for 40 years, I thought I'd try to understand the reasoning behind the original design. So far, nobody seems to know for sure.

You named it. “Reasoning”! I’ve found that at times there is no reasonable logic behind anything having to do with a RV.

[Muggs]

Just a guess but thinking setup is "self contained" primary source, external power secondary. We frequently run on race trailer gen all night. If it was to fault in hot weather and we needed A/C, just need to start internal from inside.

I really do not know why internal is primary power source other than less wear on shift? Simple matter to swap in ATS. I check mine periodically for signs of loose connections.

[Pete'sMH]

Originally Posted by Wiley1

Of course I could do that. I was an electrician in a previous life.



But, before I pull out a screwdriver to redesign something that has been around for 40 years, I thought I'd try to understand the reasoning behind the original design. So far, nobody seems to know for sure.

“For sure” is a pretty high bar….I think it’s done the way it is as a matter of control. Why would you start the generator if you didn’t want to be using it?

[MJC62]

Originally Posted by Pete'sMH

Why would you start the generator if you didn’t want to be using it?

I believe this man get's the cigar!

[16ACE27]

Originally Posted by Pete'sMH

“For sure” is a pretty high bar….I think it’s done the way it is as a matter of control. Why would you start the generator if you didn’t want to be using it?

Exactly!

[camperguy99]

Well I can think of a reason. Probably not a good one but here it is. When at my winter CG electric is $0.20/KWH. The transfer switch draws some AC current for the coil so $ lost, but my biggest complaint is it "hums" quite loudly.
Need to get out the "kill A watt" meter and quantify the cost. Might be quite low but unknown at the time.

[Axis25.2]

Originally Posted by Muggs

Ours will always go to generator if started. When I exercise gen, I kill breaker to shore power, then start and load with A/C. Always run for 30 to 45 minutes minimum when gen door open. Later versions of my unit have vent installed in door.

ATS connections get checked every 6 to 9 months.

Have you asked Thor for a vented generator door replacement? It's obviously a problem with our models, or they wouldnt have added the vents.

[Beau388]

Originally Posted by camperguy99

Well I can think of a reason. Probably not a good one but here it is. When at my winter CG electric is $0.20/KWH. The transfer switch draws some AC current for the coil so $ lost, but my biggest complaint is it "hums" quite loudly.
Need to get out the "kill A watt" meter and quantify the cost. Might be quite low but unknown at the time.

My PPS 50 amp auto transfer switch does not have a shoreline coil; only a generator closing coil and a hold close coil. My ATS is totally a pass-though device when in default mode (shore line).

I assume you have a EMS as well as an ATS in the same box. An EMS will have a dual wound energizing relay. The main coil is the closing coil (closing the points) and the small coil is the hold close coil (keeping the points closed). If it makes much noise, it could be the closing coil is not releasing when the points are closed, as the hold close coil is really low amperage so it doesn't overheat the relay when in continuous use. Usually, all continuous duty relays have dual coils.

[MLP]

Originally Posted by Scubawise

Because if power goes out..cpap dogs etc ok

If I ever have my CPAP quit do to power outage, I will connect it to the house batteries. I did this when we had a fifth wheel. Lost power twice. It is not nice waking up trying to gasp for air. So far I have not done this in the Palazzo. The 12V outlet is on the wife's side of the bed below the mattress. I will add a 12V receptacle when we cross the country again or have a park outage. I do have a 12ga extension, but do not want a trip hazard for my wife. - I like to sleep with my eyes closed!

[dkoldman]

Originally Posted by Wiley1

I absolutely understand what an ATS does. In the Navy we called it an ABT: automatic bus transfer. You can only have one source of AC power to your distribution panel. Having them both connected at the same time would be a disaster for a whole slew of reasons. In addition to being a safety device, it is also a convenience device. Because it is automatic, the user doesn't have to know when to pull down on a big switch handle.

My question is about priority. When both sources of power are available, why would the ATS choose to give priority to the generator over shore power? That seems backward to me and, so far, nobody here has been able to explain the reasoning for it.

If you have a Generac system at your house, which do you think is given priority? The utility power or the generator power? To me, an RV should be no different.

I agree with you here. My SOB system is / wired the same way from factory as TMC as I have same Southwire ATS. It defies logic to me that if power was available from both; the Generator would be used, but that is the way they are wired.

However, I fixed it

Part of why I bought the EC-30 is to do exactly what you say and that is have my Generator start Automatically if there is lost of Shorepower. With the EC-30 you have option to put the shorepower sensor before or after the ATS. I had mine wired before the ATS. So my Genset really know if it is true shorepower or not. If it is wired after the ATS; the EC-30 will not know if power is sourced from Genset or Shorepower and can loop. The latter is useless to me.

But here are a few advantages if you have the EC-30 and this option Shore Sensor Before installed. (Note: this was an aftermarket MOD for my coach installed by an Authorize Onan Dealer, they extended my warranty when I did this )

1. If I am in AUTO or Quiet Time mode and connected to shorepower, my genset will not start
2. If I am in AUTO or Quiet Time mode and generator is running, but say I plug up shorepower, the EC-30 will shutoff the Generator (think driving to a camp site on a hot day, you leveling and setting everything up but ACs are still running off the Genny . You finally get around to connect the 50amp shore cord and the EC-30 shuts down the Genny for you.
3. I am connected to shorepower and all is well, but there is a power outage, If I am in AUTO or Quiet Time mode the Genset will start automatically base on rule of Quiet time of course. When power is restored it will shut down the genset automatically.

There is more but you get the idea.

[Wiley1]

Originally Posted by dkoldman

Part of why I bought the EC-30 is to do exactly what you say and that is have my Generator start Automatically if there is lost of Shorepower. With the EC-30 you have option to put the shorepower sensor before or after the ATS. I had mine wired before the ATS.

I can't imagine why anybody would wire the sensor AFTER the ATS. That makes no sense. When the ATS is switched to generator, it would be sensing the output of the generator when the real question is whether shore power is available.

[dkoldman]

Originally Posted by Wiley1

I can't imagine why anybody would wire the sensor AFTER the ATS. That makes no sense. When the ATS is switched to generator, it would be sensing the output of the generator when the real question is whether shore power is available.

Actually it a function of the design of the rig, or how much money one is willing to pay to have it wired BEFORE ATS.

Yes for you and me, you would think that BEFORE was the only way but it is NOT. It does make me wonder for a Rig that had the EC-30 part of the OEM installed how is it wired in most or all cases? I don't know the answer.

But in my case the EC-30 did not come with the RV. I bought later and paid a hefty fee for an Authorized Onan Dealer to installed. About a month later, I was trying some advanced features like emergency backup power and it would not work. Went through a test routine and learned that it could NOT sense shore power Went back to the Dealer to find out why and they were like that feature is really not used I was like why... then they talked about how difficult it was to run wiring all the way to driver side neat the ATS. They didn't think I would need it.

They had to connect a 110vac receptacle next to the ATS, and then buy a 24vdc adapter (maybe it was 12vdc). That adapter plugs into the outlet that is always hot if there is Shorepower. It was an extra $300 to do, I wanted EVERYTHING that little EC-30 could do. I admit, I don't have too many situations where I worry about power being lost for genset to come on, but mine will do it. I do like and use all the time where the genset shuts itself down when shore power is connected.