Solutions to Auto Transformers Dangers using 230V Inverters in North America
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- Опубліковано 24 лип 2024
- Many folks are using various Auto Transformers on 230V International Inverters in order to make 120V 0 120V Split phase 120/240V.
We show the possible pitfalls in doing so, and how to remedy them (in some cases)
sometimes unbalanced phases are inevitable - you be the judge.
Often, pennies saved by doing this can be far outweighed by possible risks.
Where possible, use a unit designed for North America
There were lots of comments and requests to highlight issues on the previous video.
00:00 Introduction
08:17 My Solution 2 yrs ago.
08:30 Why we need a neutral in a 240V US North American Breaker panel
10:28 Tripping the breaker to your Auto Transformer
11:34 Voltage fluctuations between phases with(out) the Auto Transformer
12:26 High Solar Voltage 200V +(PV ) Precautions for proper DC breakers
13:32 Cheap PV Breakers - beware!
16:13 Correct labeling for the North American Market (assuming no N & G bonding)
16:44 4.6kVA unbalanced load test on 5kva Auto Transformer - Heat Test
22:20 After 20 mins of load test
23:30 After 30 mins load test
23:48 8Kw Inverter running 5kva load for 30 mins on a 5kva Auto Transformer 237F at an ambient 33F
24:49 If there was thermal protection in the Transformer - conclusion
Awesome video Ian. You covered all the good stuff. Loved the demonstration with the light bulbs.
And holy cow those failed circuit breakers were wild! Yikes. And those arcs are crazy!!
No, not really. This video is a perfect example of doing it wrong.
1. Always use the correct rated/required breaker for the application
2. Always use at least the recommended wire size or better.
3. Transformers should directly power a panel and never parallel to the source without overvoltage protection.
Doing it wrong will always have potential pitfalls and possible failures. Instead of the recommended 32 amp breaker, why did you choose a 40 amp breaker? Why not use a 60 or 100?? The video makes no sense.
It would have been a better use of time to show the correct installation for an autotransformer application.
@@owenjones7732 he’s doing this video as an instructional video, I’ve been to his place listening to at least his end of the phone call, it seems people are always telling him how to do it. So this video is an Instructional video on visual replies to conversations he has had on the phone with customers.
Thank you for your videos. Having removed human remains from house fires years ago (as a volunteer firefighter) I’ve always respected fire. It has no emotions. You search and search for good answers, watch hours and hours of video only to find it’s not as simple as it looks. Again thank you.
Put a lot on the brain 🧠 here. But what I really want to see is a in depth on those 4 5kwes feeding into the 12kw . Love to see the diagram and the explanation. I hope people are not getting sensitive here bcuz we are all after the same thing. Safe reliable self sufficient electricity at the best price point. Good 👍 vid. Thx and big up
You technically do not need a combiner box for the 5000es, NEC guidelines say that you can parallel 2 strings without fusing, just grab an IMO switch and an MC4 splitter
Thank you for taking the time to demonstrate how dangerous this is.
You are a moron. A 120/240 inverter includes a transformer. Is reality that difficult for you?
Ian one thing I've found, that at least with my LV5048 which I purchased from you ironically the actual inverter at least when in inverter mode will go into protect before the breaker even trips. Not sure that it applies here but I do wonder if the all in ones actually do a better job of protecting you than the breakers. We have shorted things just as you said and the inverter has gone into protect and I consider this a great safety feature. Amazing video!
Great information!
Excellent video. I've tried to explain this but people have not understood and some even try to claim I'm the ignorant one. 🤣
Yikes on those breakers! They must not have much distance between contacts. Or maybe no blowout magnets? I've found 2 panels in series is plenty for my 48v off grid system. Higher voltages are way more dicey.
Nice video.
When used to split the inverter output or balancing should have adequate transformer capacity or maybe use a thermal switch on the autotransformer and a relay that disconnects the inverter feed into the panel. I have an auto transformer that I plan to use to operate a 220v minisplit from a 110v inverter.
Thanks for the upload,
At time stamp 16:00 what's the model of your "Combiner Box"?
I guess I need to pay my school fees 🙃 LOL.
This is Brilliant !!
thanks for the video and heads up i had no idea of these problems was just about to buy 2 grow watt 5000 and atuo tranz... looks like ill go with two mpp lv6548. unless someone tells me not too!
Check out 8:18 in the video. It looks like Ian combined a 5000ES with a 12KW Low Freq inverter. The 5000es supplies 240 input to the 12KW and gets the split phase 120 from the 12KW Inverter which has a built in transformer. Looks like it gets around the problem with the 5000ES.
But aren't there cheaper/simpler ways, like buying a US market single all-in-one split-phase unit?
Thank you! so you think id be better off with 2 EG4 3kW Off-Grid Inverters for each leg than a 5kw growwatt with auto transformer? signature solar also recommended getting a soft start unit for my deep 2hp 220 well pump
Hi Ian, have you seen the Victron 230/240v 50/60hz inverter units that have programable ground options and "talk" to the Victron auto transformer? (an oversimplification) but I have heard the case made for a large 240v (10-15k VA) inverter with a large 24000VA autotransformer (this assumes offgrid setup). Wanted to get your thoughts prior to shelling out money for the setup.
Thank u for making this video. Not sure what to do with my growatt 5000es and the auto transformer I just got. I was thinking I could do the bypass/ grid assist before your last video. I think I could set it up to a off grid split ac unit 240v.
See if they will take it back for a refund. Unfit and dangerous for purpose.
Just install and use them. Just use the right wire size. Plus if you bought from signature solar? You can ask them and they will help you set up properly. Ian undersized the wire to the auto transformer and breaker box. Please pay attention to details. The auto transformer has 8 gauge wire. He put 12 or 14 gauge in his demonstration. Undersized wire creates heat. I have a few videos of my awesome solar set up. I never made videos before. So the three are rough but they are truthful. They also power my house and I have a well and 8 different heater’s running. The inverters that I bought from someone else. Other than signature solar did not handle the loads. You did notice he said to buy inverters with an auto transformer already in them. Auto transformer’s are used everywhere. They rarely fail. Just wire everything properly and use the right gauge of wire.
@@jamesshomesolarmore2223 - “you heard him say”
You also heard him talk about the problem of the auto-transformer not having a thermal sensor, no thermal sensor going back to the inverter, and consequence of shut off of the auto-transformer by breaker or failure or thermal shutoff (if there was a failure.)
An undersized wire being replaced with a thicker wire, will not address any of those concerns.
“Just installed them and use them”
You did not address the trust of his concerns. You brought up a “red herring”, which did not invalidate the thrust of his concerns.
Telling others that the “red herring”, which does not resolve the safety concerns highlighted, is sufficient to move ahead with confidence, is a logical fallacy.
If you would have said “size the wires correctly”, put a temperature sensor on the auto transformer, with a circuit to shut off all the inverters feeding the auto-transformer - then you would have appropriately addressed more of these safety concerns highlighted.
Instead, you brought up a relatively minor point, and told someone to falsely be assured of their safety.
That is dangerous.
People must be aware of the safety concerns, risks, and make the decision themselves… not given a false sense of security.
if you are reading double the current in neutral then you have reverse polarity in the center tap ...
2:50 Do not ever install separate grounding electrode systems. They should ALWAYS be bonded together. Another issue that can occur is when there is a ground fault on the primary system serving the utility transformer. The utility ground voltage can rise significantly. In one case on a solar project I worked on, it was shown to be 500 Vac across the entry gate to the solar system. That could kill somebody.
What about solar racking, where the racking is isolated from the single panel ground, because the panels are frameless.
Should the racking ground be a separate ground?
Yeah that is what Ian said in the video.
Starting about 16:22 with the G L N markings, trying to clarify context: are these Non-split phase inverters that have been adapted to North American split phase? Perhaps the markings on the hardware were not updated?
Yes, the "G-L-N" labels are the European markings. This inverter is being "hacked" for use in the USA (240 split phase)
Is the problem of this using an autotransformer? Would using an isolating transformer from 230V to the 115-0-115 make the load dump issue go away? Is this what the pole transformer does?
The SolarEdge and Growatt '5 kW' isolation transformers are really 2.5 kVA autotransformers. Marketing has creatively decided their advertised rating is based on 50% 120vac imbalance.
As you found, a transformer can be overloaded for a limited amount of time. At 5kVA 120vac imbalance you have less than about 30 minutes before transformer gets dangerously hot on these '5 kW' , 30 lbs weight autotransformers.
It is downright dangerous to put one of these on a 5 kVA inverter without some transformer protection. Minimum protection is a thermistor/thermocouple on auto transformer that controls a double pole 240vac breaker on output of 240vac inverter to open the 240vac from inverter when transformer exceeds about 70-85 degrees C.
This is what Victron autotransformer does. They use a temp controller that controls a solenoid trip attachment (S9 solenoid) on a ChiNT NB1-63H dual pole 240vac breaker.
The SolarEdge unit has an embedded K-type thermocouple between windings and transformer core, but you need the temp controller and breaker solenoid trip to make use of it. The original SolarEdge inverter had inputs for the thermocouple to shut down the inverter if autotransformer got too hot.
If you have a DVM or theromocouple meter that uses a K-type thermocouple you can use the SolarEdge thermocouple to measure transformer temp.
What about off grid stand alone system? I'm using mine to backup my refrigerator and freezer. Maybe some led lights
I just released a whole home power video test it came out amazing.
What if the inverter L1 L2 are connected to the double-pole AT breakers, but the critical load 240v are connected only to the AT L1/L2 (after the AT breakers) ? when the AT breakers pop, the critical panel also loose 240v. No 240v flash/zappo
@@JohnBaker3000 Ian wired the inverter outputs L1&L2 directly to the Critical Load (CR) box. The AT is connected through a double-pole breakers to the CR to generate the CR's Neutral. When the AT's breakers pop'd, the inverter L1&L2 are still driving the CR loads; but now without the Neutral. My suggestion is to put the double-pole breaker right at the inverter L1/L2 outputs, before the CR load box
I use these inverters but don't use electric heaters. Most of my load is 240 volts for water heating since I have hydronic heat. I also run 120 volt parasitic loads like phone chargers, power tool battery chargers, the refrigerator, and a bunch of LED lights. I barely see any load on the AT. The 240 volt load has no effect on the AT. I'm going to add more of the 5000ES (US) when I add another air to water heat pump.
Just buy from signature solar and please get advice from them. I can give you their phone number if needed?
Awesome Lesson sir! Why would someone use a 5kva auto transformer with loads capable of anything near 5kva or over 5kva? If I use 3, 5kw growatt inverters I'm going with a 20kva transformer at the least. They have already spent the money for the system. They have money! Do it right! And I agree Get the western made inverters first.
I'm a poor fellow but taking that kind of short cut will kill me in my sleep.
You were running at close to 2x unbalanced max rating (3kVA = 25A on neutral). Max temp spec is 60 degs C (140 degs F) so at 235 degs F (113 degs C) you were well above limit.
It appears the transformer is winding wire limited as windings seemed hotter than core. This is not surprising as the wires looks like only #20 or #18 gauge. That would also explain why you got so much voltage drop (105vac) on loaded side.
If you have a DVM or thermocouple meter that takes 'K' type thermocouple you can hook onto the Solar Edge 'K' type thermocouple mounted against transformer core under windings. Terminals for thermocouple are small terminal connector between AC connections and transformer. The Solar Edge inverter has inputs for the 'K' type thermocouple to shut the inverter down if autotransformer gets too hot.
Would be interesting to know how many minutes it takes to get to 60 degs C (140 degsF) with 25A neutral load with lid closed.
👍🏾
Tell us why you didn't consider using an isolation transformer from 2 wire 240V input to 3 wire 120V X 2 output instead of the Auto xformer
Does GroWatt offer one? Price?
Can someone help explain if the autotransformer breaker trips why would there be 240v coming out the neutral and L1 or L2 from the critical load panel? I can see the inverter was connected directly to the critical load panel sending 240v to L1 and L2, but I still cannot understand why there would be 240v from L1 to neutral ??? If the neutral is generated by the autotransformer and the breaker trips, there shouldn’t be no neutral leg at 120v in the panel… someone explain please ? Thank you all, great content by the way !
I had to take a minute to figure this out myself, I think this is the answer:
The AT takes 2 wires from the inverter, at 0V and 240V. There is a tap on the transformer coil that runs back to the neutral bus of the panel.
This centre tap providing neutral is actually at 120V to ground.
Now, with the AT running, in the panel you have 2 legs of 120V, as follows:
L1: 0V (inverter) to 120V (AutoTransformer neutral) = 120V difference.
L2: 240V (inverter) to 120V (AutoTransformer neutral) = 120V difference.
If the AT disappears? Neutral goes from 120V to 0V. Therefore:
L1 to Neutral is: 0V to 0V = 0V. So the light bulbs on the L1 side turn off.
L2 to Neutral is: 240V to 0V = 240V. So the light bulbs on the L2 side get 240V, and turn off in a fun way.
@@dpddpd71 I think it is because this sub-panel is fed from the top by the inverter 240V (L1, L2) and the autotransformer is fed L1and L2 by a 20 amp double-pole breaker and establishes the neutral which is fed back to the neutral bus bar. When the double-pole breaker trips, you lose the neutral but you still have 240V total across the two legs. The loaded-down leg that caused the trip has lower impedance to ground (the neutral bus is connected to ground at some point like at the main breaker) so it gets close to ground and the 240v mostly appears on the opposite leg at least momentarily and blows that leg's two bulbs. That's the best I can rationalize it but I wish the guy would explain this a little better.
Will the 6000t also work in bypass mode? Is that feature on the 6000t? I too have a 6000t and 2 of the 5kes but have not installed the 5kes only the 6000t
Yes it works perfectly in bypass mode
@@watts247 what setting number is that?
Thanks for your video , I am installing a 7kw solar system to charge a Tesla with 240 V would also like to use 120 v to power a small fridge and lcd lights and a few ipads and lap tops. What Inverter would you suggest I buy that is made for US . I am looking at two LV 6548 would that work? I have a propane stove and hot water heater. My main power use would be the 240 to charge a tesla and 120 volts to power a fridge that draws about 200 watts. I will be OFF GRID and .
Do you think the LV 6548 would work if not what would you suggest. I will have three LL4 48 volt batteries 5.12KWH 100 AH per battery Thank you
LV6548 units would be great and so would the 5000ES with an isolating transformer, 240 in 120 out.
I would get 2 5000 es inverters and a auto transformer. Plenty of power and you never have to worry about failures. Just make sure to use proper wire size.
@@jamesshomesolarmore2223 - didn’t we just watch a video about the Auto Transformer risks? LOL!
If you are going to avoid an Auto Transformer, to avoid the risks outlined & demonstrated in this video - look at a Genetry Inverter. They do a true split-phase 240v with 120v per leg.
They make a real Low Frequency inverter with a built in transformer, which has cooling according to the unit temperature sensors, temperature alerts, and thermal shutoff protection for the whole inverter.
Their 6K unit is shipping today, handles surges ~12K, and works with 48v batteries.
They are developing a true 12KW low frequency inverter, which should handle a surge up to 24kW.
Yes👍 🔋⚡💡
quick question, does a normal transformer solve the issues? sure the 240v loads are going to suck more power as you're only magnetically coupled, but you have isolation then.
An Isolation transformer ( 240V AC L1-L2 input to 240 Split-Phase L1-N-L2 output ) solves a lot of problems.
@@MrSummitville That's what I did. Glad to see you agree 👍
@@kstorm889 There are some 3-wire (L1-L2-G) 240V appliances / devices that do not use a Neutral Wire - like a well pump, hot water tank, clothes dryer, stove, heater, a/c, etc. They do not need to be connected to the transformer, which would reduce the size and cost of the isolation transformer's
@@MrSummitville one caveat, some dryers use 120 for the motor and the controls, same with controls on some ranges. But things like my welder and compressor run straight on 240
@@kstorm889 Note I said, "... 3-wire (L1--L2-G ) appliances ...". If the appliance needs a 120 v motor then it would have a 4-Wire Plug ( L1-N-L2-G).
Forget using a transformer of any kind when there is a large load difference between L1 and L2. The voltage between L1 to N and L2 to N will be different and not 120V any more because of transformer internal resistance/inductance. A stable split phase system requires an inverter that regulates L1 to N and L2 to N independently. This will keep the voltage and phase fixed independent of the load on L1/L2. We can use two inverters with 120V output that synchronize with each other to keep the phase between L1/L2 at 180 degrees combining it to 240V. MPP Solar has inverters that can do that, like two 3048LV-MK, one LV5048 and one LV6048. These are high frequency inverters. SMA offers the low frequency 6048-US inverter where two combined will do the job well.
So what's the pros/cons of using 2 120v inverters 180 out of phase and then a single 240 output with an auto trans (for off-grid)?
Each inverter keeps output at 120V and 180 degrees to other independent of load. Makes a stable system Auto trans can't do this because of transformer internal resistance. More power on one phase creates larger voltage drop on this side. The other side will go up in voltage so different voltage on L1 and L2 Inverter regulates output to 240V but has no control of individual phases.
I feel sorry for frying those perfectly good incandescent light bulbs getting fried.
Auto-transformers do have inherent imbalance currents if you have imbalanced loads. Isolation transformers are way much more stable. An auto-transformer is a cheap version of an isolation transformer. This type of transformer is not usually used for large loads.
Hi, Ian, I just made and released my Growatt and SolarEdge transformer video. it was a test using more than 10,000 watts of 120-volt loads. I would like you to review it and comment. I know my video's lack the professional touch. But the content is accurate.
The autotransformer would do better with the inverter set at 240V and 60hz (edit: specifically - it would produce less heat), especially running it at 50hz means that it automatically needs to be upsized by about 20% for the same V.A.
All auto transformer concerns highlighted (like accidental breaker switch off, unbalanced let’s, grounding issues, etc.) are not mitigated by increasing Hz from 50 to 60x.
It may address a percent of the issues related to thermal concerns under load.
It seems the auto transformer isn’t worth all the risks. Remember folks it isn’t how well it works.. what is important is how well it works when something goes sideways.
please check the testing I just released. If your house is wired correctly? you won't have any issue. My video goes into some of the wiring, and I tested my transformer at over 10,00 watts of 120 loads. Also, if you want awesome amounts of power and protection for your appliance's? they have surge protectors and gfci plugins. the gfci test was included in my test video.
Lot of this is due to piss poor knowledge in electrical, good circuit isolation is key, you need to make sure that there is very clear decisive separation of each stage of conversion, transformer must all ways be larger then the inverter! Breaker must all ways be smaller then the inverters max out, any circuit interruption must cut all phases (I use 3phase CB on my inverter so it isolates all lines) or I run it off the 120v only. and my rule is any CB 2* max operating voltage for the DC side.
Inverter -> Auto Xformer -> 3Ph CB -> Distribution Panel
Too bad. These little transformers have a big place in the market....but you can't get them anymore. I need one...but only want to push at the very most 3kva (inverter limit) as a step up. But....now...I can't get it because too many people hurt themselves with it. 🙄
This is not true. You won't have 240 on one side, and nothing on the other. You will have 240 from N1 to N2. The light bulbs did not blow because of them having 240 volts, but they blew because now all of the current on the left phase is trying to go thru the right side light bulbs.
Reality is that you have 240 volts, and the voltage drop of all of the loads in series must add up to 240volts. So, since the load of the saw, and heaters pulled 20 amps (for example), the light bulbs had to allow 20 amps (which the bulbs could not support). The voltage drop across the load still exists, and since the auto transformers no longer balancing the phases, the phases are forced to be equal and hence 20 amps is forced thru the bulbs.
The real problem here is that he has loaded everything on one phase. Had half the heaters been on phase 2, then there would have been minimal current thru the neutral, and the current that needed to flow thru the light bulbs would have been shared with the heater.
So, the real lesson here is to always BALANCE your loads as best you can when you design the system.
To prevent losing neutral balance in case of autotransformer breaker trip you have to connect autotransformer directly to inverter and rely on inverter input breakers to trip both the inverter grid input and autotransformer together. This way it's impossible to get 240v on one 120v leg. Essentially this turns this 240v single phase inverter into hardwired split phase 120+120v source. All else is valid. The transformer needs to be placed in cooling oil or blown with forced air along with temp sensor to shutdown the inverter in case of xformer overtemp.
Why did you undersized the wire to the auto transformer? You do know that undersized wire produces heat?
Minimum wire size should be 8 gauge.
Makes me wonder if you undersized all the wires in this demonstration?
You're quite right
43A on neutral was good for demonstration, and worked well. It proved the point.
@@WillProwse will I have used my auto transformer powering my whole house with 8 heater’s and air conditioning plus a well pump. During the spring and summer we have radial arm saws and table saws plus air conditioning all running through the auto transformer. So why doesn’t mine trip?
@@jamesshomesolarmore2223 sounds like a lot of 240V loads, which wouldnt require the auto transformer. I have no clue how your system is wired or the output capacity. How about you post a video of your entire system so we can all see it.
Ian love your demonstration, please never wire anything for me. If you are going to do a demonstration? Please use proper wire size’s.
Explain how can you love the video with that critical assessment
For which demonstration? They were all straight forward and were good examples of the points that Ian was making.
It's a demo, not a permanent install! Ian proved a point on the consequences of using the transformer. Get a life!
@@WillProwse will you did spot the improper wire sizing on the transformer? Small wires cause heat.
@@8894larry then he should use the proper wire size. Using undersized wire will produce heat. Learn and question every demonstration. The transformer is a 5 kw. It needs 8 gauge wire.
Ian I can get every inverter you sell to fail. Just by under sizing the wire’s. This is just a dog and pony show. Do the same demonstration using proper wire size.
James , thanks you for being the top commenter on this vid. You mentioned you made a lot of videos on your solution, please share with us on YT so we can all learn.
Tks
@@watts247 I do have videos on UA-cam. You have my name just search for me.
@@watts247 I do believe that you have good products. But I believe in the 5000 es inverters and the solar edge transformer.
@@watts247 I have 5 video’s that’s it.
James can you explain what you think would be so different, with thicker wires, in this demo?
Because I see absolutely nothing that Ian talked about where wire gauge has any bearing whatsoever.
For open air / chassis wiring, and distances as short as the panel->AT run, 12 AWG is rated to 40 amps. The NEC does not apply the same code to chassis spec, as to bundled transmission wires (half the rated amperage) which is what you are apparently fixated on.
Still, not a single topic of the video has any relation to wire size, it's completely irrelevant to all of Ian's points, which means you probably just didn't understand any of them.