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Aims 10kw Inverter Shuts down

the_uglydog

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Joined
Sep 11, 2020
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Location
Luzon, Philippines + Orlando FL, USA
Hi, We are in The Philippines but use the same type split phase electric grid as at home (US). We have an Aims 10kw off grid inverter that is powered by separate charge controllers which produce about 14kw. It is set up to clip the excess when it's sunny and in the middle of the day so that when it's cloudy and rainy we still have power. When I first installed it last year in March it would only take a 20% load then shut down with an overload fault. That is the end of hot season and the beginning of typhoon season here and we had been having a lot of heavy rain and heat, 100*F and 95% humidity. I used it with only a small load till mid summer and I then noticed it took a larger load. It kept taking a bigger load and after about a month it would load to 90% no problem and was working fine ever since. UNTIL the first Typhoon this year in May, now it won't load beyond 30%. A repair tech here found a couple of bad chips and changed them but it still won't load beyond 30% most of the time. He says he thinks the relay is bad. Aims is no help at all, either to me or him. This unit is supposed to be for marine use so it should be able to take humidity, right? I thought maybe there was water getting into one of the building's circuits, so I shut them off one at a time but the problem persists. Could an input wire from the utility that is leaking electricity cause something like this? The grid here has wildly varying voltage from 230 down to about 175. I have it set for the wide range down to 173 and it worked fine all year. Any thoughts would be appreciated. That's about it, the dog
 
won't load beyond 30% most of the time. He says he thinks the relay is bad.
Doesn't sound like a relay to me as they're on/off type devices, not 30% of max power.

Could an input wire from the utility that is leaking electricity cause something like this? The grid here has wildly varying voltage from 230 down to about 175. I have it set for the wide range down to 173 and it worked fine all year. Any thoughts would be appreciated.

A shunt or a meter on the inverter should be able to tell you what the output is. If there was any sort of short-circuit draining power the shunt/meter should be inside that loop.

How are you coming up with the 20%/30% numbers?

Could you provide a diagram of your electrical hookup between the grid, inverter, battery, and load?
 
Hi, I've used a clamp meter on all the lines and tested at the input and output terminals of the inverter as well as at the terminals of the breakers, inverter bypass switch (a generator transfer switch that manually bypasses the inverter to the utility when needed) and at the generator transfer switch to get the actual amps, there's no high draw and no voltage drop between any connections. The 20-30% is off the display on the inverter. I've also disconnected every circuit one at a time, including every load circuit, the combiner boxes and utility, same exact problem. All DC wiring is routed along the outside of smooth galvanized pipe to the combiner boxes, they are weather proof and dry inside, from those it's inside ventilated conduit, (open at the bottom open end weather head at the top) then into the boxes through insulated connectors. Inside the power room all DC is loomed together with nothing sharp near them. All AC lines are loomed with nothing sharp near them into the main breaker panels. Entrance to the panels has plastic insulators. From the main panels some circuits go to sub panels, all entrances to panels are protected by plastic insulators. The main output breaker on the inverter is 120 amps, main panel breaker is 100 amps and sub panel mains are 60 amps. The grounds are at the drop and a second at the inverters. All of the inverters are grounded at the same location as is the neutral/ground from this inverter and all neutral/grounds form the load side as per the instructions for the inverter. There is no voltage drop between connections. We used 4 10' ground rods wired together. Also there is an additional grounding system for the panels, combiner boxes and mounting system through lightning arrestors 100 ft from the grounds for the system itself. All AC wiring is routed through plastic conduits. I was thinking that moisture may be getting into one of the circuits in a sub panel, but I've tried shutting them all off as well one at a time. I'll look through the plans, I'm sure there's a diagram, if not I'll make one and I'll get pictures of it all. The DC wiring; from each combiner box the wires feed to a charge controller, right now 4, each of those feed through separate breakers to the + and - of the batteries. The batteries connect through separate cable through a breaker to the inverter. Everything works fine when connected to the utility no breaker trips and no overloads the main from the utility is only 100 amps. It's odd that this would work OK for almost a year then go back to the same problem it had before, at the same time in the year. It was also the beginning of hot season here, day temps 100* humidity 95%. Now the temps are about 80*-90* and the humidity is about 75%. Ask me anything, suggest anything, it will be appreciated. the dog
 
The 20-30% is off the display on the inverter.
What does the inverter do when you try to exceed 30%? Is there a specific device you're trying to turn on that won't come on? If so, what is it?

...All of the inverters ...
How is the output of multiple inverters being kept synchronized (aka stacked)? I didn't see any models of Aims inverters with a parallel feature. Here's a link to their website, can you tell us what models you are using to generate 10 kW? https://www.aimscorp.net/

... if not I'll make one and I'll get pictures of it all....
That would make it easier and you'd probably get more feedback. For me posts like your previous fall into the category of How to increase the odds of getting a response to your thread as the text-block description is hard to read/comprehend.

...Everything works fine when connected to the utility...
  1. From the clamp meter, how many amps off the grid does the system pull with everything on/running?
  2. What is the battery voltage?
  3. How many amps is the BMS rated for?
  4. At the 30% load, what is the amperage from the battery? What is the amperage on L1 and L2?
At 30%, does the inverter fan come on? In the 10 kW manual it says the fan comes on only when the load is > 30%, half speed up to 50%, and full speed above that. So, that might provide a clue other than the display reading.

It's odd that this would work OK for almost a year then go back to the same problem it had before, at the same time in the year. It was also the beginning of hot season here, day temps 100* humidity 95%. Now the temps are about 80*-90* and the humidity is about 75%.
What's the highest output you've seen on the inverter when it was working?
Does it happen all the time, or only certain times of day in the summer (e.g., fine at night, but bad at 4 pm)?
Does the grid work okay in these conditions?

Have to wait for your grid hookup schematic, but I thought the AIMs had a built in transfer switch, so if the grid frequency or voltage is off it ought to cut in and take on the load. Given the care with which it sounds like you've taken to protect the wiring from humidity and critters, I'm not sure it is the humidity or temperature directly, but I could see your neighbors AC cause dirty enough power to cause problems.

Ask me anything, suggest anything, it will be appreciated.
What is your favorite Color?
 
BTW, it doesn't sound like a short is what's limiting your power. If it were the inverter would display it was running at 100%.

Could be something like a temperature sensor or fan (e.g., it's hot so it kicks on the fan, but it's not cooling so it limits power to it's no-fan max of 30%). Will know more when you've had time to respond to the post above.
 
Hi,
1. When it reaches 30% it alarms for overload and shuts down. I have numerous critical load circuits on it. It has been running, all the house lights, one standard 110v fridge, two 220 v bar fridges one standard 220 v inverter fridge, three 1 hp inverter type mini split a/c units, two 3/4 hp inverter wall unit a/c's, (50%, 50 amps AC, 65 amps DC, when all are running, 24-34%, 22-34 amps AC and 40 amps DC when only 2 mini splits and the 2 wall units are running and the fridges and a/c's have been running and reached operating temp) adding 3 microwaves and one hairdryer it runs up to 90%. With everything on it reaches 90% on the screen, about 80 amps AC and 100 amps DC. I have tried turning different things on one at a time to get to 30%, it doesn't matter what it is, it shuts down. Last year when we had the problem initially all that was hooked up was the house lights and 2 wall a/c units, I wired everything else up one thing at a time and it's been OK since last July.
2. Sorry, we have multiple inverters but they are all independent systems. The Ames is an Aims 10kw Global LF Series Inverter. It runs critical loads with generator backup. We have 2 Must 5kw units that run 2 a/c's each on a separate drop, one Growatt 8kw grid tie on a separate drop running the pool pump, the 5 living area a/c mini splits a/c and the irrigation pumps, a separate drop for the cell tower and 4 guest houses and a 12kw inverter on a separate drop for our deep well pump and the water system pressure pump.
3. When running on grid the AC current reads the same as when the inverter is running. Voltage readings are the same across all the drops and at the inverter hookups on all units.
4. Battery voltage, (right now we are still using gel batteries, LifePo4 are on the way) can be anywhere from a high of 57v DC to a low of 44v DC, it doesn't seem to matter, it cuts out at 30%. Batteries were lasting about 6 hours on a full charge.
5. The inverter fan comes on at 24% on low, speeds up a bit at about 34% and is on high above 50%. It did take a 50% load for about one minute and the fans were all on full.
6. Amps on both lines are off by about 3 amps and voltage is about 1 volt, I tried to split the 110 between the 2 lines evenly but a bit more is on the low one.
7. I have the Aims set to battery priority so it stays on batteries no matter the input voltage and switches back to utility at 44 volts DC. It is set to wide utility input range 173v AC low and 266 v AC high. When on the utility and it drops below 173 v the inverter disconnects but the power stays on. At the time of year the problem started is the beginning of hot season, utility voltage can range from about 166 v to about 200 v with the average of 185 v during hot season. It had been over 100*F for about 2 weeks prior to the problem starting and the problem started after the first typhoon and a lot of wind and rain. It was working OK even with the low voltage and didn't shut down when the Growatt unit alarmed for the 166 v a couple of times. When the LifePO4 batteries arrive we will air condition the power room. Right now utility is at 207 v ranging 200 v to 220 v.
8. It shuts down at 30% all the time, we aren't running it right now. I try every day or so it but it keeps shutting down and I don't want to damage it.
9. RED!
Schematic and photos to follow shortly. That's about it. the dog
 
...I have numerous critical load circuits on it. It has been running,...With everything on it
reaches 90% on the screen, about 80 amps AC and 100 amps DC. ... a time and it's been
OK since last July...to a low of 44v DC
10kW inverter at 120V is 10,000 /120 = 83 amps, looks like the Aims can support
surge up to 3x, so ~240 amps.

Although that 100 amps DC is wrong, 10,000 / 44 = 227 amps (might want to
check your battery wire gauge/temperature).

Well, that might be the problem...see the image to the right...

insp_expendability.jpg


...the problem started after the first typhoon and a lot of wind and rain...
Nothing leaked on it? It was snug and dry through the event? Would anything from outside have crawled inside the nice warm/safe/dry inverter?

... alarms for overload and shuts down...
Overloads can happen with shorts across the power transistors (internal rather than external short) - and that can happen with bugs getting zapped across the power lines. That it happened before and magically fixed itself might have been that a bug zapped itself across the power, then when the bug became desiccated it no longer shorted anything.

Could also be heat-related. Something like the air intake/exhaust/fan-blades are not optimal (e.g., dust, spider webs, dead critter), or the exhaust/in-take is just too close to a wall or shelf and when it's really hot it's just not getting enough air. Does anything feel hotter than normal (other than the weather ;-)?

If you can do so safely, might be worthwhile to take the lid off and take a look. Possibly some canned air (don't blow canned air on hot electronics though, the canned air is very cold)
 
Here's pictures of the electrical system. Wiring diagram to follow.
 

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Well I guess you got it! I was wearing red when working on it!!! :LOL: I'll switch to a blue work shirt. We had a repair company disassemble it and they cleaned it and replaced some components, now it reads the right voltage but still shuts down. It's a lot cooler now, daytime high 85* with about 60% humidity. I check the temperature of everything regularly when it was working correctly with a touchless thermometer and when it's hot out we use a large fan to keep air moving over the inverters. When the inverter fans aren't on, the upper left side is a bit hotter than the rest but as soon as the fan kicks in it drops back down. I test the temp of the wires and the breakers, all are warm to the touch, but not hot, when it's loaded up high. But under it's normal load of 20-40% nothing is more than warm. I forget the actual temp exactly it was around 110 *F under load and room temp with the small normal load. I may have gotten the DC reading incorrect, I did it a while ago and was giving the reading from memory, of which my wife says I have none. I have 2/0 cable for the battery and a 250 amp DC breaker. I do find lizards in the outside breakers at the drop all the time, but I haven't seen any remains inside the indoor panels and I don't think it got wet, but the wind was about 80mph so stuff was really blowing around. There is lots of dirt in the air here and I will be insulating and air conditioning the power rooms to eliminate heat, humidity and the dirt. These pics are from the main power room where all but the 12kw inverter is for the well and system pressure pumps, it's in it's own room. The Aims won't even carry the load when it's first turned on, I wait till all the voltage readings have come up to the correct level and turn it on, as it loads everything is fine, in the 20+% range the internal fans come on and when it reaches 30%, the fans come on high, alarm and off. It doesn't matter the utility voltage, the battery voltage or which circuits I use for the load, it's the same. I had been thinking it could be the heat or the humidity, it's supposed to be Marine Grade, but here we slightly exceed the humidity. As soon as I can get the scanner working I'll upload the wiring diagram. That's about it, thanks. the dog
 

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Nice setup!

I did see some knock-outs that had been removed and should be plugged less critters & weather get in, but nothing that would cause your problems.

Problem Recap
Let's check I have this correct (plus a short version should help any EE's that visit the thread), correct anything incorrect:

Problem
Aims 10 kW Inverter gives overload alert and resets between 20 to 30% load capacity (as based on inverter display), on grid though inverter's built-in ATS all works okay.​
History
Aims Inverter connected to grid and 48V battery. Everything is fine when on-grid and used to be fine on battery.​
Last year in the hot/humid season the Aims also wouldn't output more than 30% on battery without faulting due to overload, the problem went away as the season changed.​
This year the unit was serviced to correct a voltage problem where they replaced a couple of chips (?) and it worked fine until the hot/humid season started. Now it faults again between 20-30% capacity. Fan works, plenty of air-space around the inverter. No changes from prior setup.​

Hmmm
Because everything works on-grid I'm thinking the problem is isolated to inside the Aims. Has anyone had the lid off and looked inside since the problem started after the typhoon? High voltage caps in there so be very careful even if unplugged! Another failed component or bug that committed bugicide and is causing a short/fault is still my best guess.
 
From page 10 of user manual:
Caution:
After the inverter is switched on, it takes a finite time for it to self diagnose and get ready to deliver full power. Hence, always switch on the load(s) after a few seconds of switching on the inverter. Avoid switching on the inverter with the load already switched on. This may prematurely trigger the overload protection. When a load is switched on, it may require initial higher power surge to start. Hence, if multiple loads are being powered, they should be switched on one by one so that the inverter is not overloaded by the higher starting surge if all the loads are switched on at once.
 
Consider pulling the cover off inverter and spray with dielectric grease, if available.

 
Your recap is correct. I do wait about 5 minutes after switching the inverter on to add loads and I add them one at a time as you said. One day I switched it on and waited about 4 hours then tried it, same thing, overload alarm and off. I'll try that again today since it is a lot cooler and drier. Yes, I had a guy check it and he replaced some electronic components and cleaned it, the voltage reads correct now, but it still does the same thing. We have not been using it since it was hooked back up after the repairs. The guy that does the repairs seems to know what he is doing, he does warranty work for almost every manufacturer and travels throughout PH to work on inverters for the power companies. He just didn't seem to know why it would act this way, he tested all the internal parts and replaced everything that was out of specs. Once he showed Aims what he found, he could no longer get a response from them. Here's the wiring diagram, I hope you can understand it OK, if not just ask. the dog
 

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Anything I can think of your repair guy probably already did.

Current is from a number of mosfets working together in two sets, one for each leg (L1 and L2). If one leg were dead the other would be limited in its output, but easy to test. Similarly some mosfets could be dead, but also easy to test (even without tools as the live ones are hot).
The temperature sensor could be giving a false reading leading the system to curtail power, but also easy to test.
If all the hardware is meeting specs, that leaves a fault in the firmware?

Don't suppose you have something like a FLIR to image the inverter internals while operational?

What do you think @Supervstech? (See #12 for a recap) Any ideas?
 
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Agreed.
Humidity affecting the chips
Chips are sealed, humidity shouldn't affect them... but moist dust across the leads... that could sure do it.

Any (easy) way to drive moisture out of the air to see if it makes a difference?
Possibly a dehumidifier in the same room?

If it does make a difference I'd look real close/hard at removing all traces of dust inside the inverter (with a soft-bristled paintbrush and compressed air) and then similar to @mopat's suggestion use some sort of conformal coating. Although I'd use a spray-on made for circuit boards with multiple coats ;-). The grease he recommended is more for removable connections... you want your coating on the PCB to cure/harden otherwise it'll attract dust.

Aims is no help though?
Aims isn't calling his repair shop back.
 
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All the lines are hot, they always are almost exactly the same voltage and amp reading. Sometimes one is a bit lower as more 110 is on that leg. The 110 is reading 1/2 of whatever the reading is across both hot lines. I'll use a temperature sensor gun to check everything today. I tried a portable a/c unit blowing on it. I left it running 4 days blowing at all of the inverters, same place as the green fan in the picture. No difference. The humidity is down a lot so far this week, we'll see what happens. I ordered an a/c unit for the room and a temp/humidity switch and I'll seal the room up and try that. I was wondering about the humidity as well, the Aims is supposed to be marine rated, but who knows.... No, Aims is no help whatsoever! They talked to the repair guy until he showed them what he found then never responded again, that's exactly the same response I got last year. This year they told me the board was defective, but they're out of stock, so I had that guy repair it. Thanks. the dog
 
I temperature checked everything today. As a baseline, the concrete wall near the inverters is 89.7*F. The Growatt 8kw Inverter at 5kw output is 93.1*F, the Must 5kw at 1kw output is 92.3*F. The Aims, with no load, at it's coolest spot 89.9*F, hottest spot 95.6*F. At 20% load, at it's coolest spot 90.3*F, hottest spot 96.5*F, at 29% load, at it's coolest spot 90.3*F, at it's hottest spot 96.5*F. It ran for 10 minutes at 29% as soon as it went to 30% it shut down and alarmed overload. The DC main temp with no load 88.4*F, 20% load 89.0*F, at 29% load 89.0*F. The AC main at no load 93.5*F, at 20% load 92.6*F, at 29% load 92.6*F. I don't know why it got cooler, I checked it twice. Thanks. the dog
 
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