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Automatic Transfer Switch (Moes) vs Inverter

Heydk

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My new 1500 w solar system with 200ah Lifep04 batteries and 3000w inverter using an ATS tapping into grid power when the battery runs low, was working fine for about 5 days. Then early the other morning I suspect right after the ATS switched back to using the inverter, my wife put a large draw on the system and it failed. Specifically the inverter went into Overload and started beeping. It's fried as far as I can tell. It turns on but goes into OL everytime - but that is not my question. The strange thing was at the time the system failed and after I turned the inverter off - the ATS display indicated that it was using the batteries to power the load (the HVSW value was met) when the inverter was off when in actuality the load was being powered by grid power! This I couldn't understand. I'm getting a new inverter but I'm afraid to connect back up to the ATS - any suggestions? If the inverter is off when the ATS hits the HVSW would it know this and continue to supply power from the grid?
 
I guess I dont understand the question.

If the inverter is off, the ats should default to the active power source...
What is hvsw?
 
HVSW - high voltage switch - the voltage, when obtained by the battery, the ATS will switch to use
battery power
 
... If the inverter is off when the ATS hits the HVSW would it know this and continue to supply power from the grid?
An ATS switches to a secondary power source when it detects no power on the primary source. To "throw" the switch takes power, so the ATS uses the power from the secondary source to throw the switch, reasonable since there's no power on the primary and no reason to switch if there's no power on the secondary.

Usually the primary is the grid and the secondary the backup. In your case that's reversed. So, what might be happening is that the switching power is being provided from the inverter. That is, as the power dips the switch flips but there's still enough battery power to throw the switch. In the case of a sudden shut-off (e.g. overload or flipping the inverter's switch off), there's no power to throw the switch. I'd suggest contacting the manufacturer to make sure, possibly just needs the primary/secondary switched and HVSW logic reversed?
 
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An ATS switches to a secondary power source when it detects no power on the primary source. To "throw" the switch takes power, so the ATS uses the power from the secondary source to throw the switch, reasonable since there's no power on the primary and no reason to switch if there's no power on the secondary.

Usually the primary is the grid and the secondary the backup. In your case that's reversed. So, what might be happening is that the switching power is being provided from the inverter. That is, as the power dips the switch flips but there's still enough battery power to throw the switch. In the case of a sudden shut-off (e.g. overload or flipping the inverter's switch off), there's no power to throw the switch. I'd suggest contacting the manufacturer to make sure, possibly just needs the primary/secondary switched and HVSW logic reversed?
Svetz, The ATS is powered by the batteries and the ATS does the switching based on the low-voltage and high-voltage switch values that you set on the ATS. The switching power is not provided by the inverter. What it comes down to is that I need to do some testing before I hook up my new inverter. As far as having the grid and the inverter wires reversed I don't think that is the case as the system worked fine for nearly a week and the display on the ATS was accurate. It does make sense that if the inverter was off or in overload status when the ATS detected the HVSW value was at the voltage to switch to inverter power that it would continue to provide grid power. It's just that the display on the ATS indicated the power was coming from the inverter - when it wasn't.

Now - what fried my inverter, that is another question.
 
Sorry it wasn't useful.

....As far as having the grid and the inverter wires reversed ...
I meant reversed from a typical ATS application, that is an ATS is more frequently used to switch to a home to generator when the grid goes down, where the grid is the primary and the generator the secondary.

I have no experience/knowledge of a Moes ATS or your setup where the grid is a secondary source. What I was talking about was how a grid/generator setup works and suggesting it might be relevant to your setup. In those setups there is also a battery, but generally its just a relay that triggers the generator's startup motor. Generlink makes an another type of ATS that sits behind the meter; the ATS only flips when the secondary source has power, that is you have to manually turn on/off the generator to get it to flip to/from to the primary.
 
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Sorry it wasn't useful.


I meant reversed from a typical ATS application, that is an ATS is more frequently used to switch to a home to generator when the grid goes down, where the grid is the primary and the generator the secondary.

I have no experience/knowledge of a Moes ATS or your setup where the grid is a secondary source. What I was talking about was how a grid/generator setup works and suggesting it might be relevant to your setup. In those setups there is also a battery, but generally its just a relay that triggers the generator's startup motor. Generlink makes an another type of ATS that sits behind the meter; the ATS only flips when the secondary source has power, that is you have to manually turn on/off the generator to get it to flip to/from to the primary.


I have one of those ATS in my boat, there is a pic HERE if it helps you help the OP, as said it gets its power direct from the battery and you set the high/low battery voltages at which you want it to switch from one power source to the other and back.
 
I have one of those ATS in my boat, there is a pic HERE if it helps you help the OP, as said it gets its power direct from the battery and you set the high/low battery voltages at which you want it to switch from one power source to the other and back.
Popuptoaster - thank you for the pics. Your system is very similar to my system but I have an EPEVER CC and a 3k/6k inverter. What's funny is the first 24v device I added was a boat bilge pump with an automatic float switch. I have a regular AC sump pump in the crawl space of my house - but when the grid power goes out I wanted a backup. My wife thinks I'm trying to turn our house into a boat - ha. You said you live on your boat - are you on the east coast or the west coast? My house is on an island in Maine. There is a bridge so I don't need a boat to get here thank goodness.
 
I live in the UK, the boat is moored in a tidal area so when it's beached i can't run the engine for power, hence the solar. At the moment I have access to shore power but eventually that will be replaced by a generator when I go travelling.
 
I live in the UK, the boat is moored in a tidal area so when it's beached i can't run the engine for power, hence the solar. At the moment I have access to shore power but eventually that will be replaced by a generator when I go travelling.
So sorry, naive of me to think you were from the states. I understand your desire to supplement with solar on your boat. I was a full time RVer (caravaner) and did a lot of boon docking. Had to have solar to survive.
 
Hi, I'm sorry to hear about your inverter. Do you think the transfer switch was to blame? I just got the same unit and have been messing with it just today.

It seems like it's a dumb switch. If my inverter is off it will still try & switch to it.p

Have you tried changing the switch points to see if it is still working correctly? If it's still hooked to the battery you should be able to raise & lower the voltage settings & get it to click back & forth?

What type of inverter was it & how many watts was the load?
 
Hi, I'm sorry to hear about your inverter. Do you think the transfer switch was to blame? I just got the same unit and have been messing with it just today.

It seems like it's a dumb switch. If my inverter is off it will still try & switch to it.p

Have you tried changing the switch points to see if it is still working correctly? If it's still hooked to the battery you should be able to raise & lower the voltage settings & get it to click back & forth?

What type of inverter was it & how many watts was the load?

Hi Jak,

I'm not sure it was the ATS or not. Since I have a dead inverter (Giandel 3000w 24v) I hooked it all back up and tested the ATS to see what it would do with the inverter connected but off. The ATS seemed to work perfectly. When the inverter blew the ATS display said the power was coming from the batteries (inverter) but the inverter was dead yet the load was still being supplied with power (from the grid?) must have been coming from the grid. When I just tested the ATS with the dead inverter in off position I figured the ATS would be smart enough to know the inverter was off and continue to supply grid power. Instead the ATS would switch to battery (based on display) and no power was supplied to the load. So, when my inverter fried and the ATS was showing power coming from the batteries why was the load still being powered? Did that somehow fry the inverter? I don't know. What I do know is that Friday I get a new inverter and I'm afraid to hook it all back up.

My setup is powering an AC sub panel with 3 20amp breakers. One circuit is for a refrigerator (med size) the other two circuit are basically just outlets powering a couple computers, a modem and at the time of failure my wife just fired up a coffee maker that draws about 700w. In any case everything on the three circuits would only add up to about 15 amps and certainly not hit the 6000w surge limit on my inverter. Even if it did the inverter supposedly has an Overload protection which I guess did not work. I have since pulled the cover on the inverter and it has 6 30amp fuses all of which are fine. Why didn't they blow? I wish there was a way I could analyze the inverter to know what is wrong with it. Have you grounded your inverter? On the Giandel there are two ground points - one with the load out wires and one to the case. I only had the one connected along with the load out wires? Could that have caused an issue - I wouldn't think so.
 
My new 1500 w solar system with 200ah Lifep04 batteries and 3000w inverter using an ATS tapping into grid power when the battery runs low, was working fine for about 5 days. Then early the other morning I suspect right after the ATS switched back to using the inverter, my wife put a large draw on the system and it failed. Specifically the inverter went into Overload and started beeping. It's fried as far as I can tell. It turns on but goes into OL everytime - but that is not my question. The strange thing was at the time the system failed and after I turned the inverter off - the ATS display indicated that it was using the batteries to power the load (the HVSW value was met) when the inverter was off when in actuality the load was being powered by grid power! This I couldn't understand. I'm getting a new inverter but I'm afraid to connect back up to the ATS - any suggestions? If the inverter is off when the ATS hits the HVSW would it know this and continue to supply power from the grid?
  1. I don't know about most inverters but my 2000w 24v Giandel (and I would think your Giandel) have overload protection to prevent inverter damage. If so and it died then I presume yours has the same 18 month warranty as mine by which to get it replaced.
  2. To understand what's going on with your inverter (short of a tech support call) you should have a "battery monitor" meter such as found on this page, installed between the batteries and the inverter. You may also need a "Kill-A-Watt" meter in order to understand what demands are actually being placed on your inverter by the 110v stuff plugged into it. Troubleshooting my system would have been quite difficult without either meter. (Also, the provided link shows a good, basic DIY 24v system and safeguards, and other DIY solar projects. You might compare the photos with your setup?)
  3. Turning off the inverter will not cause the ATS to switch from battery to shore power if the batteries are still above the ATS "low-voltage switchover voltage." You have to turn off your ATS in order to force it to switch to shore power (or wait for battery voltage to drop sufficiently). The ATS cares only about what the batteries are telling it through its 12v monitoring connectors.
  4. You say the ATS display indicated it was using battery power but that that power was really coming from shore power. As another commentator said, unless you have the "shore power" and "solar/generator power" connections backwards, and assuming the ATS isn't defective, this can't be. If the ATS indicates it's switched to battery then it's accepting power only from your inverter. I suppose it's possible your shore power is somehow hooked in between the 110v outlet on your inverter and the "inverter incoming" connectors on the ATS, though that sounds like a recipe for failure and equipment damage.
  5. (My problem is similar to yours except that, now and then when I check it in the morning, I find the inverter has powered off. I think this is due to the fact the inverter, just sitting there, draws a certain amount of current. This means that, though my ATS has switched to shore power do to low-voltage from the batteries, the batteries, already at low voltage, continue to drain through the night until their protection circuitry kicks in and they power off, forcing the inverter to power off. VERY unfortunately, there is no way to set the Giandel to automatically turn back on when batteries charge to acceptable levels. Accordingly, when the batteries charge up sufficiently during daylight the ATS reaches its "high voltage turn on" voltage and switches back to "solar" -- but the inverter is still off, so my freezer and such don't run until I manually turn the inverter back on!"
I hope this helps, some.
 
It does sound like it was either hooked up backwards. Public power / inverter (Which I've done & it doesn't hurt anything) Or it somehow was back feeding your inverter. Could be a faulty transfer switch unit too. However without knowing exactly what was going on. It's hard to say. Could be something else, like just asking too much of the Inverter. I'm no expert but I agree with the above post. A kill a watt meter is a must have. An AC/DC clamp meter maybe could help diagnose the problem as well.

I have been concerned about the possibility of the ATS back feeding too. & I'm not positive. Maybe someone else knows. But I'm thinking a gfci inline with your inputs may help make sure that doesn't happen?

I was considering something like this

But, I think I maybe returning mine though. I'm purely off grid & was hoping I could use it as a normal ATS by reversing the inputs & using my generator in the inverter input & spoofing the battery voltage with a 12v wall plug. I read on Amazon & on YouTube comments saying that should work, but for some reason. When doing it like thay it doesn't switch fast enough to keep the Direct TV box from having to reboot. There's something else going on I don't quite understand. Because it only works for me (switches fast enough) if I pull out the 12v DC wall wart. Shutting down the generator makes the power transfer lag too much & lights flicker & electronics reboot..
 
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I have the pictured ATS. Like others said, I'm pretty sure that when the voltage gets back up over the HV threshold it will switch back to the inverter input even if the inverter is off. It is NOT smart enough to check for voltage at its input before switching. In fact I sketched out a simple relay circuit that would work around this after I bought it, but I never got around to making it. Basically, use the inverter's output to hold in a N.O. relay that supplies the battery connection to the ATS. When the inverter is off, the relay would open and the ATS wouldn't see battery voltage, so it switches to, or just stays on, shore power. Could use a SSR, or any small relay - the ATS' battery input doesn't carry much current.
 
A thought, but it's not likely: If you had a surge/spike that welded the ATS relay in the "grid" position (or burned out its coil), then the ATS likely would display normally that it was in the inverter position after the battery voltage was above the HV setting. But it would actually be supplying grid power thru the welded contacts (or due to a disabled coil, because the relay is directing grid power to the load when the relay is not energized). However, I don't think this scenario would back feed grid voltage into the inverter. Do you hear the relay clicking when switching to grid and then back to inverter inputs? Regardless, I would check the ATS inverter input connections while it is on grid power to see if there is a (significant) voltage present. (Without an inverter connected.)

Other thought: If you pulled a surge of amps that caused the bms to shut off the battery, during the day when your SCC was charging the battery, the SCC wouldn't have liked it. This might have caused a voltage spike when the SCC shut off its PV input, and that overvoltage tripped your inverter. Still, I wouldn't think that would damage your inverter, because that kind of overvoltage shouldn't be excessively high.
 
  1. I don't know about most inverters but my 2000w 24v Giandel (and I would think your Giandel) have overload protection to prevent inverter damage. If so and it died then I presume yours has the same 18 month warranty as mine by which to get it replaced.
  2. To understand what's going on with your inverter (short of a tech support call) you should have a "battery monitor" meter such as found on this page, installed between the batteries and the inverter. You may also need a "Kill-A-Watt" meter in order to understand what demands are actually being placed on your inverter by the 110v stuff plugged into it. Troubleshooting my system would have been quite difficult without either meter. (Also, the provided link shows a good, basic DIY 24v system and safeguards, and other DIY solar projects. You might compare the photos with your setup?)
  3. Turning off the inverter will not cause the ATS to switch from battery to shore power if the batteries are still above the ATS "low-voltage switchover voltage." You have to turn off your ATS in order to force it to switch to shore power (or wait for battery voltage to drop sufficiently). The ATS cares only about what the batteries are telling it through its 12v monitoring connectors.
  4. You say the ATS display indicated it was using battery power but that that power was really coming from shore power. As another commentator said, unless you have the "shore power" and "solar/generator power" connections backwards, and assuming the ATS isn't defective, this can't be. If the ATS indicates it's switched to battery then it's accepting power only from your inverter. I suppose it's possible your shore power is somehow hooked in between the 110v outlet on your inverter and the "inverter incoming" connectors on the ATS, though that sounds like a recipe for failure and equipment damage.
  5. (My problem is similar to yours except that, now and then when I check it in the morning, I find the inverter has powered off. I think this is due to the fact the inverter, just sitting there, draws a certain amount of current. This means that, though my ATS has switched to shore power do to low-voltage from the batteries, the batteries, already at low voltage, continue to drain through the night until their protection circuitry kicks in and they power off, forcing the inverter to power off. VERY unfortunately, there is no way to set the Giandel to automatically turn back on when batteries charge to acceptable levels. Accordingly, when the batteries charge up sufficiently during daylight the ATS reaches its "high voltage turn on" voltage and switches back to "solar" -- but the inverter is still off, so my freezer and such don't run until I manually turn the inverter back on!"
I hope this helps, some.
1. Yes - it is being replaced under warranty.
2. I have battery monitor.
3. I've tested my ATS since my inverter was fried and it appears to be working perfectly. Before the inverter died it was also working as it should.
4. Right after my inverter started beeping and displaying OL (Overload Status) is when the ATS display indicated the energy source was from the batteries/inverter - which it couldn't be due to inverter being in OL status. The load was still being powered - and it had to be from city power. This is the only time the ATS did this. After I turned everything off and tested the ATS it worked as it should. I have/did not connect up my shore power in a strange way. It is exactly like Will set his up and besides it was working just fine for nearly a week before the inverter conked out.
5. I'm concerned that when I get the new inverter that the same thing may occur. I have to do some thinking about what I might do to prevent a similar outcome.
Thanks for you feedback.
 
Any update on why your inverter quit working? I have the same setup with a Moes ATS and Giandel 2000/4000 inverter running a refrigerator. Worked fine for 3 months then Invert went to OL status, ATS switched. Giandel replaced the inverter but suggested a possible back feed issue. Tested the ATS and all seems good. Any update would be appreciated.
 
Any update on why your inverter quit working? I have the same setup with a Moes ATS and Giandel 2000/4000 inverter running a refrigerator. Worked fine for 3 months then Invert went to OL status, ATS switched. Giandel replaced the inverter but suggested a possible back feed issue. Tested the ATS and all seems good. Any update would be appreciated.
I'm running the same Giandel 2000/4000 inverter with a MOES ATS and had the same OL experience in less than 6 months. I hope your replacement inverter fares better than your first.
 
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