Yes, I have the SPF6000T and I find it works better when I disconnect the AC supply. I thought that low frequency inverters were better but now that I have that information, I won't be using inverters with an autotransformer when there is grid back up.
I think you can put a 100A two pole contactor (if for instance you are feeding 70A, like with the 12k model) with a 240v coil inline in between the breaker feeding the incoming 240v and the inverter. Use the line side (incoming) aux contacts (the side with incoming from 70A breaker) to feed the coil on the same contactor. That way if a phase is lost the contactor will immediately open until the phase is returned on the line side of the contactor. It should open in that millisecond transfer of the inverter. You can also do a similar thing to the outgoing neutral to protect from single phasing such as with a three pole 240V contactor. Similar things are done to protect compressors with a phase loss in the HVAC industry. Worth a try.
These models already have fuses and breakers on the outside. Mpp on the inside. Breakers and fuses are not really the issue I'm explaining, it's the fact that your auto transformer is trying to balance loads on the grid side
@@id007rx Pretty sure I didn't say anything about putting a breaker or fuse in it. I said put a (240v coil) two pole contactor inline (in between) the breaker (main/sub) feeding the inverter and the incoming breaker on the bottom of the inverter with the coil voltage being fed from the main/sub (line side) feeding it. If you lose one phase such as you described by removing that black wire in your subpanel, the contactor will open, (simulating off grid) and stay open until that one line side of the 240v of the contactor is restored. The auto transformer only tries to balance the load when you lose one phase of the incoming side of the inverter such as you kept doing by removing that black wire in your sub panel. A contactor will prevent that. You can buy 240v motor protector relays that do the same thing but a contactor is cheaper and it does the same thing. If unsure look in any A/C unit and you will see what a two pole contactor looks like. Those are 24v coil voltage but you can buy 240v coil contactors that do the same thing. You can also do the same thing with a simple contactor to remove the outgoing neutral/ground bond if a phase is lost. That's the path (neutral) the unbalanced load is traveling on back to your main/sub panel. Hope that helps explaining.
@@MiniDigging It's a good idea but the contactor will not open for imbalanced loads. For example you could have 110V on one leg and 120V on the other and 50 amps going through your auto transformer.
@@mrfrenzy. That's true. Having an imbalanced load is the owners fault if everything is operating correctly. You can easily switch breakers up one or down one slot in your panels to balance out your own loads. In his video he was creating an imbalanced load by (single phasing his inverter input). The contactor method I suggested would prevent an imbalanced load "caused" by losing one phase of incoming power to the inverter. It's easy, simple, cheap and would prevent the scenario he created in his video. That scenario he showed is very unlikely, but could happen. I would be more concerned with a neutral/ground bond issue if something like that happened. That's why I suggested doing the same contactor thing with the outgoing power of the inverter which includes a neutral. Growatt and others could easily implement this into their inverters but no one has suggested it to them it seems.
They (manufacturers) could all solve this entirely by incorporating a isolation transformer instead of the cheaper single wound auto transformer. That's the only real solution
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid.
@@pemcs if you know there is a storm coming and could loose grid u may want to charge from grid. But that's irrelevant. This issue happens even when not charging. Anytime in bypass mine puts load on the neutral. Load that isn't mine. But my neighbor's. I Installed a 3 phase 200 amp contactor that isolates the neutral and hots for my mechanical bypass. So I have no tie to the grid neutral when the system is running normally
Your understanding of how that inverter works is completely mistaken. That big lump of iron and copper is NOT an autotransformer. It is a transformer with a low voltage primary, and a center tapped mains voltage secondary. The inverter circuit synthesizes (using high frequency PWM) a low voltage (about 30 V) AC waveform. That low voltage ac is applied to the primary, which is the massively thick wires visible on the transformer. Hidden below those is a secondary winding with many turns of much thinner wire. The primary and secondary are isolated. How would I know? I am an engineer and at an earlier stage of my career designed AC power conditioning products. Not inverters, but I certainly know in great detail how they work. I also have an inverter of the type you showed. It is Sigineer brand, but clearly identical internals. I understand the confusion, as calling it a "low frequency" inverter denies the fact that the 60 Hz sine wave is created by high frequency pulse width modulation. On the other hand, what the industry calls "high frequency" inverters do the voltage step up BEFORE synthesizing the the 60 Hz sine wave. A DC to DC converter stage steps the battery voltage up to about 350 volts DC using a small, light, high frequency transformer. Then the 60 Hz sine wave is synthesized by pulse width modulating the high voltage DC, which directly creates 120 VAC. There is one very significant electrical difference between the two topologies. The so-called low frequency inverter topology can flow power from the AC side to the DC side! And that means it can act as a sink for the power coming from a grid interactive inverter. I had a previously existing grid tied solar system at my house before I got the Sigineer inverter and batteries. Like all such systems, if the grid was down, the solar panels were useless. But now the Sigineer can act just like a grid, able to absorb power, and my solar panels and their grid interactive inverter see its output as a grid. They push the AC power they create to the Sigineer's output side, and that power can flow backward through the Sigineer "low frequency" inverter and charge the battery (if the house is consuming less than the panels are making.) This happens sort of automagicly. There is not a separate charging circuit that does this. The fact that it can happen is an inherent property of the topology. The PWM FETS on the low voltage side of the transformer are acting as synchronous rectifiers. This is called an AC coupled solar battery system, and is an effective way to add a battery backup to a previously existing solar system that creates AC power. Not as efficient as directly using the DC from the panels to charge the battery, but much more practical than completely re-doing an existing system that was originally installed without battery backup.
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid. Only time I charge from grid is if grid failed and no solar. I use an interlock to switch from grid to generator then change settings to charge from grid and at that point I'm the only one using the generator. Then it will try to balance my loads via the internal transformer? I am very familiar with PWM signals. I install and maintain thousands of VFDs in the plant I work at and learned long ago how they work using PWM to synthesis variable frequency and voltage mainly because I used to used them to generate 3 phase at home with only single phase in for my machine shop. I've since moved to rotary phase converters of my own construction as I collected more and more machines it was no longer practical to have a drive on every machine vs a single power source. Thanks for the new explanation. I'm confident it's over most people's heads
Take the transformer disconnect the low voltage side of it from the fets. Now what is it? It's an auto transformer. I own one of these and I did the test. I had zero load on the inverter. And yet I had current flowing through one leg and neutral. I was in parallel with my neighborhood pole transformer and essentially getting charged to help balance the pole transformer loads coming from my neighbor's. I had to break code to make it ok. I completely disconnected the neutral from my grid panel. The only thing my grid panel feeds is this inverter. Then the output feeds my main house 200 amp panel. The ground rod is connected to this panel and bonded in this panel. There is no connection from the main panel and my grid panel. So no my bond is no longer at the means of first disconnect but oh well.
Great video and very informative like always Ian Anyways, I just had my growatt 11.4 KW auto transformer fail It fried the boards in so many appliances in my house. It’s not even funny. I was running 3 5KW growatt units from signature, solar there US model
Great information about the Growatt. If L1 and L2 are protected by a 60 amp breaker and you use the appropriate 6 AWG copper wire, if/when a line fault/imbalance occurs and you exceed 60 amps on one leg, the breaker should trip -- correct? Do you have clamp meter readings on the neutral where is exceeds 60 amps? Guessing you would need to have a line fault and a massive imbalance on your subpanel to create this condition, since relatively balanced loads on panels have little current returning on the neutral. Curious to hear your thoughts.
The breaker should trip? You are missing the point, OFF is OFF, not back-feed when off and a breaker will trip if over current. In addition, I do not understand your comment on 'little current returning on the neutral', where/how is it returning if not the neutral?
@@GruvyTubie Didn't intend to hit the third rail on this one. Also don't think I missed the point. "OFF is OFF" is incorrect, because if there was a switch cutting the circuit to the 2nd bulb, it would remain off. The bulb turned off because he simulated a missing leg {I typically don't turn my lights off in my house by disconnecting the L1 lug on the panel :) } The video demonstrated that Growatt Inverters running in bypass mode do not detect a L1/L2 single leg disruption -- instead act as an autotransformer and completing circuits on the "dead leg" in the subpanel. Finally, your question about how current flows in a 240/120 single phase system, I recommend looking at ElectricianU video "Does Current Flow on the Neutral?" he does a great job explaining apprentice electrician materials. Thanks
I had my growatt auto transformer, wired house signature Solar told me to when it failed and never tripped either in or out breaker which is how they suggest wiring a unit. I fried all sorts of boards and appliances through my whole entire house. I’m lucky place did not burn down I was pumping almost 400 V between the two legs. Lucky thing was my son who’s an electrician was home an shut everything down Immediately
I think your slighly confused. I use a 10k LF (low frequency) in verter i support 4 dwellings ( trailers) lights evaporative coolers refrigerator and tv. I bonded my centertap neutral of the transformer to ground! This eleminates all mismatch voltages. I ran my oscilloscope and no noise in the signal. So ground the center tap neutral and this stops .This is why i believe your confused.
:( Pity. I bought one of the LVX6048s from watts247 and it's powering most of my house with grid tied but back-feed turned off. I liked that I could use one box to get 120 and 240v. Was also told the transformer would help start my 2.5HP compressor. Wonder if I should consider changing inverters?
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid.
@@bigcbradioI have one system for my whole house. This inverter 70kwh lithium batteries Generator interlock that chooses between my solar or grid. Also have the "grid" connection for the inverter on a plug. I can choose to plug it into the actual grid or my 12kw diesel military generator. I don't grid charge because I have a generator. If the grid goes down and a cloudy winter day. I can start the generator and use it to charge the batteries and run the house. A full charge with the cloudiest days I can usually go three days. In the summer with both central air conditioners running (4 tons total) I can go 1.5 days if its hit outside. Click click Machine shop radio on the side
I think that's a good catch on what's possible. But its so contrived that I'm confused about your deduction. I've never seen one leg go down to cause this. 240V breakers are linked so that both poles turn off at the same time. If you create this scenario in real life then you should probably stop trying to be an electrician and call in a professional.
Ok I own one. I just ran the experiment. Your missing the point. Even when u don't loose a leg when in bypass your inverter transformer is trying to balance the neighborhood transformer. What I just did is this. I put it in bypass mode without grid charging. With would be the same. But I don't charge from grid ever. Solar charging only. I took off all load from inverter. Inverter on In bypass due to low battery. I had current on my grid neutral and hots.... So this transformer is balancing in parallel with the pole transformer. Now being properly breakered for the wire will prevent damage. My biggest issue is this now I'm pulling power through my utility meter that I'm not using. I'm now paying for power my neighbor is using and so is he. This is absolutely unacceptable! The point of solar is to reduce my electric bill not pay for my neighbors when my batteries go low and it enters bypass mode.... I'm going to have to isolate the neutral somehow... I'm pissed.
Let me give you a real world example. I have a lvx6048. I had that same exact scenario. I had some bad weather so I decide to use my grid to charge my battery. I lost one leg. The wires that come from the supplier is that black covered aluminum wire that connects at my pothead that is joined to copper wire. Copper and aluminum does not like each other. About 4am I got an error code on my inverter. It was very quiet so I could hear the arcing noise on the roof. I went up there and the aluminum was turning to dust with intermittent electrical contact. It cost me my main board in my inverter that I have since replaced. So that how you lose a leg. Better safe than sorry
@@bigcbradio You maybe right but that job was done by so called professionals. But that's apart of life and thats why we have things like reverse polarity protection and a ton of other protection that most times trigger by human error. So where is the protection for this one. Its clearly designed flaw one that I would prefer to avoid.
@@bigcbradio safe is when something goes wrong a protection circuit kicks in. Safe is when a gfci switch shuts down when water gets into it. You could argue that not having water near it is safe. This house was connected more than 18 years to the grid.
It appears the only problem here is connecting the neutral of the input to the neutral of the output. The input shouldn't have a neutral connection at all.
is auto Transformer the regular term? I ask because english is not my native language! where i live we have 3 phases... so please do not misunderstand ! thank you for this video!
You do not need to worry about this unless you live in a country with 120V electrical outlets. If you have for example 240/400V you will not have this autotransformer inside your inverter.
Autotransformer is a proper term. While most transformers have two separate windings (and some have more than two), an autotransformer has a single winding. In English, the term "auto" means self, or a single unit. As usual, there is a connection to each end of the winding, also there will be one or more "tap" connections to the winding. If you had a winding with a tap in the center, the voltage between the tap and either end of the winding would be half the voltage. The tap could be placed at any point along the winding to get any voltage. Since there is only one winding, there is a savings in the cost of the wire and the size of the transformer. The disadvantage is that the input and output are not electrically isolated as they would be if there were two separate windings.
If this is not a low frequency inverter then what is,i respect your intelligence sir but i disagree when you say transformer based inverters are high frequency
The issue is that unless you have a switched neutral that is isolated you’re always ys going to have what you’re describing if grid connected when it goes into pas through. Doesn’t matter the design. If it is a low frequency unit it will always have this and so will an auto inverter. The only real solution is to use an isolated charger to charge batteries and never go to grid but that’s at best 94% efficient and thus expensive. You could make it better if instead of stepping down went to the 400vdc bus voltage and reinverted instead of battery voltage. Of course this goes back to the con job done to Congress in the 1930s making everyone’s homes unsafe to save power companies a little money: transformers on the poles should be isolated and the isolated side center tapped. Then there’s never an issue.
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid.
@@electromechanicalstuff2602 the issue is that the auto transformer when you go into grid bypass will then balance the grid itself because the grid doesn’t use isolated transformers. So you become your neighbor’s neutral balancing. That will cook the auto transformer because it’s everyone on your phase to the sub station net/net. If the grid was done properly instead of how Congress allowed them to get away with this wouldn’t be an issue because every house would have an isolated transformer and the secondary would be center tapped. But because cronyism and cost cutting we get lightening strikes and stupid isolation rules that drive cost up and net efficiency way down while still being less safe. The power companies just like it because the efficiency is after the meter not before. If you’re using grid charging and it stays on inverter you won’t have this issue because any UL listed box will have isolation for that grid charge thus protecting you from the imbalance. The fundamental problem is that unless there’s a relay after the low frequency transformer in a center tapped inverter the same thing will happen there too because it’s still connected to the grid neutral in bypass mode so the center tap effectively is an auto transformer at that point. And of course an high frequency transformer less design with out of phase dual inverters for generating 120+120 is getting the fets hammered if the neutral is out of balance in bypass mode. So there’s way more to this than just the auto transformer. That said, I don’t use my grid’s neutral at all even in bypass and the auto transformer has never seen more than 12 amps on it (I have an arduino with clamps monitoring it so I know if there is any risk and I need a second one)
@@jameshancock I understand that my transformer and the pole transformer are essentially working in parallel causing my transformer to become the load balancer. I only have a 50 amp breaker on my inverter because I never allow grid charging and so far no tripping. Doesn't mean it's not happening but I'm going to experiment and see for myself. Because if in the times I'm on bypass my meter is measuring power I'm not using to balance the neighbors house I may have to look into maybe installing a 3 phase transfer switch so I can disconnect the neutral from grid to my critical loads panel
You don't have clue what you're talking about. If you connect a scope or a frequency meter at the output of the FET board or the primary windings at the transformer, you'll measure 60 or 50 Hz. Besides, if what you say is true then where are the high frequency transformers, and high voltage caps and high voltage diodes in this inverter? There are none.
I own one of these. I'm not worried because I don't charge from grid.... Y would u. When my batteries die I bypass to grid but don't charge from. This prevents the transformer relay from ever being engaged in the first place. When the solar recharged my batteries it switches back to invert mode. But what he says is accurate ish. Regardless of loosing a leg or not . If you have a large imbalance from L1-L2 the transformer inside the inverter will be working in parallel to the pole transformer to balance the load. More or less
Ok I own one. I just ran the experiment. Your missing the point. Even when u don't loose a leg when in bypass your inverter transformer is trying to balance the neighborhood transformer. What I just did is this. I put it in bypass mode without grid charging. With would be the same. But I don't charge from grid ever. Solar charging only. I took off all load from inverter. Inverter on In bypass due to low battery. I had current on my grid neutral and hots.... So this transformer is balancing in parallel with the pole transformer. Now being properly breakered for the wire will prevent damage. My biggest issue is this now I'm pulling power through my utility meter that I'm not using. I'm now paying for power my neighbor is using and so is he. This is absolutely unacceptable! The point of solar is to reduce my electric bill not pay for my neighbors when my batteries go low and it enters bypass mode.... I'm going to have to isolate the neutral somehow... I'm pissed.
Thank you for the explanation makes a lot of sense. I can now understand what our problem is. They work great a stand alone, with no feed lines.
Yes, I have the SPF6000T and I find it works better when I disconnect the AC supply. I thought that low frequency inverters were better but now that I have that information, I won't be using inverters with an autotransformer when there is grid back up.
Wow. Thanks for the demonstration Ian.
Really interesting was looking to get one of these as I was under the impression they were low frequency glad I watched this, thanks Ian
I think you can put a 100A two pole contactor (if for instance you are feeding 70A, like with the 12k model) with a 240v coil inline in between the breaker feeding the incoming 240v and the inverter. Use the line side (incoming) aux contacts (the side with incoming from 70A breaker) to feed the coil on the same contactor. That way if a phase is lost the contactor will immediately open until the phase is returned on the line side of the contactor. It should open in that millisecond transfer of the inverter. You can also do a similar thing to the outgoing neutral to protect from single phasing such as with a three pole 240V contactor. Similar things are done to protect compressors with a phase loss in the HVAC industry. Worth a try.
These models already have fuses and breakers on the outside. Mpp on the inside. Breakers and fuses are not really the issue I'm explaining, it's the fact that your auto transformer is trying to balance loads on the grid side
@@id007rx Pretty sure I didn't say anything about putting a breaker or fuse in it. I said put a (240v coil) two pole contactor inline (in between) the breaker (main/sub) feeding the inverter and the incoming breaker on the bottom of the inverter with the coil voltage being fed from the main/sub (line side) feeding it. If you lose one phase such as you described by removing that black wire in your subpanel, the contactor will open, (simulating off grid) and stay open until that one line side of the 240v of the contactor is restored. The auto transformer only tries to balance the load when you lose one phase of the incoming side of the inverter such as you kept doing by removing that black wire in your sub panel. A contactor will prevent that. You can buy 240v motor protector relays that do the same thing but a contactor is cheaper and it does the same thing. If unsure look in any A/C unit and you will see what a two pole contactor looks like. Those are 24v coil voltage but you can buy 240v coil contactors that do the same thing. You can also do the same thing with a simple contactor to remove the outgoing neutral/ground bond if a phase is lost. That's the path (neutral) the unbalanced load is traveling on back to your main/sub panel. Hope that helps explaining.
@@MiniDigging It's a good idea but the contactor will not open for imbalanced loads. For example you could have 110V on one leg and 120V on the other and 50 amps going through your auto transformer.
@@mrfrenzy. That's true. Having an imbalanced load is the owners fault if everything is operating correctly. You can easily switch breakers up one or down one slot in your panels to balance out your own loads. In his video he was creating an imbalanced load by (single phasing his inverter input). The contactor method I suggested would prevent an imbalanced load "caused" by losing one phase of incoming power to the inverter. It's easy, simple, cheap and would prevent the scenario he created in his video. That scenario he showed is very unlikely, but could happen. I would be more concerned with a neutral/ground bond issue if something like that happened. That's why I suggested doing the same contactor thing with the outgoing power of the inverter which includes a neutral. Growatt and others could easily implement this into their inverters but no one has suggested it to them it seems.
They (manufacturers) could all solve this entirely by incorporating a isolation transformer instead of the cheaper single wound auto transformer. That's the only real solution
Do you think this would still be the case with a higher quality inverter? Like a Schneider or victron? Do toroidal transformers have the same issue?
I had a 12k growatt went to Solar-ark, good thing. Looks like they work great off grid. Happy with the one i had, just wanted more charging
Ian how are you doing ! this is Ernie out in Arizona, I'm still having trouble with the Growatt inverter. Left you a voicemail last week.
The way around this issue to make this safe is to run off the grid. It's an off-grid model. I get what you are saying and you are 100% correct.
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid.
@@electromechanicalstuff2602 Who uses utility to charge when there's the SUN. Why would anybody do that?
@@pemcs if you know there is a storm coming and could loose grid u may want to charge from grid. But that's irrelevant. This issue happens even when not charging. Anytime in bypass mine puts load on the neutral. Load that isn't mine. But my neighbor's. I Installed a 3 phase 200 amp contactor that isolates the neutral and hots for my mechanical bypass. So I have no tie to the grid neutral when the system is running normally
What is the solution? Proper isolation transfort wont fix it either just have to completely isolate the neutral from the grid?
Do I need a up/down transformer with off grid system
Your understanding of how that inverter works is completely mistaken. That big lump of iron and copper is NOT an autotransformer. It is a transformer with a low voltage primary, and a center tapped mains voltage secondary. The inverter circuit synthesizes (using high frequency PWM) a low voltage (about 30 V) AC waveform. That low voltage ac is applied to the primary, which is the massively thick wires visible on the transformer. Hidden below those is a secondary winding with many turns of much thinner wire.
The primary and secondary are isolated. How would I know? I am an engineer and at an earlier stage of my career designed AC power conditioning products. Not inverters, but I certainly know in great detail how they work. I also have an inverter of the type you showed. It is Sigineer brand, but clearly identical internals.
I understand the confusion, as calling it a "low frequency" inverter denies the fact that the 60 Hz sine wave is created by high frequency pulse width modulation.
On the other hand, what the industry calls "high frequency" inverters do the voltage step up BEFORE synthesizing the the 60 Hz sine wave. A DC to DC converter stage steps the battery voltage up to about 350 volts DC using a small, light, high frequency transformer. Then the 60 Hz sine wave is synthesized by pulse width modulating the high voltage DC, which directly creates 120 VAC.
There is one very significant electrical difference between the two topologies. The so-called low frequency inverter topology can flow power from the AC side to the DC side!
And that means it can act as a sink for the power coming from a grid interactive inverter.
I had a previously existing grid tied solar system at my house before I got the Sigineer inverter and batteries.
Like all such systems, if the grid was down, the solar panels were useless.
But now the Sigineer can act just like a grid, able to absorb power, and my solar panels and their grid interactive inverter see its output as a grid. They push the AC power they create to the Sigineer's output side, and that power can flow backward through the Sigineer "low frequency" inverter and charge the battery (if the house is consuming less than the panels are making.) This happens sort of automagicly. There is not a separate charging circuit that does this. The fact that it can happen is an inherent property of the topology. The PWM FETS on the low voltage side of the transformer are acting as synchronous rectifiers. This is called an AC coupled solar battery system, and is an effective way to add a battery backup to a previously existing solar system that creates AC power. Not as efficient as directly using the DC from the panels to charge the battery, but much more practical than completely re-doing an existing system that was originally installed without battery backup.
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid. Only time I charge from grid is if grid failed and no solar. I use an interlock to switch from grid to generator then change settings to charge from grid and at that point I'm the only one using the generator. Then it will try to balance my loads via the internal transformer?
I am very familiar with PWM signals. I install and maintain thousands of VFDs in the plant I work at and learned long ago how they work using PWM to synthesis variable frequency and voltage mainly because I used to used them to generate 3 phase at home with only single phase in for my machine shop. I've since moved to rotary phase converters of my own construction as I collected more and more machines it was no longer practical to have a drive on every machine vs a single power source. Thanks for the new explanation. I'm confident it's over most people's heads
Take the transformer disconnect the low voltage side of it from the fets. Now what is it? It's an auto transformer. I own one of these and I did the test. I had zero load on the inverter. And yet I had current flowing through one leg and neutral. I was in parallel with my neighborhood pole transformer and essentially getting charged to help balance the pole transformer loads coming from my neighbor's. I had to break code to make it ok. I completely disconnected the neutral from my grid panel. The only thing my grid panel feeds is this inverter. Then the output feeds my main house 200 amp panel. The ground rod is connected to this panel and bonded in this panel. There is no connection from the main panel and my grid panel. So no my bond is no longer at the means of first disconnect but oh well.
Great video and very informative like always Ian
Anyways, I just had my growatt 11.4 KW auto transformer fail
It fried the boards in so many appliances in my house. It’s not even funny.
I was running 3 5KW growatt units from signature, solar there US model
Great information about the Growatt. If L1 and L2 are protected by a 60 amp breaker and you use the appropriate 6 AWG copper wire, if/when a line fault/imbalance occurs and you exceed 60 amps on one leg, the breaker should trip -- correct? Do you have clamp meter readings on the neutral where is exceeds 60 amps? Guessing you would need to have a line fault and a massive imbalance on your subpanel to create this condition, since relatively balanced loads on panels have little current returning on the neutral. Curious to hear your thoughts.
The breaker should trip? You are missing the point, OFF is OFF, not back-feed when off and a breaker will trip if over current.
In addition, I do not understand your comment on 'little current returning on the neutral', where/how is it returning if not the neutral?
@@GruvyTubie Didn't intend to hit the third rail on this one. Also don't think I missed the point. "OFF is OFF" is incorrect, because if there was a switch cutting the circuit to the 2nd bulb, it would remain off. The bulb turned off because he simulated a missing leg {I typically don't turn my lights off in my house by disconnecting the L1 lug on the panel :) } The video demonstrated that Growatt Inverters running in bypass mode do not detect a L1/L2 single leg disruption -- instead act as an autotransformer and completing circuits on the "dead leg" in the subpanel.
Finally, your question about how current flows in a 240/120 single phase system, I recommend looking at ElectricianU video "Does Current Flow on the Neutral?" he does a great job explaining apprentice electrician materials.
Thanks
I had my growatt auto transformer, wired house signature Solar told me to when it failed and never tripped either in or out breaker which is how they suggest wiring a unit. I fried all sorts of boards and appliances through my whole entire house. I’m lucky place did not burn down I was pumping almost 400 V between the two legs.
Lucky thing was my son who’s an electrician was home an shut everything down Immediately
I think your slighly confused. I use a 10k LF (low frequency) in verter i support 4 dwellings ( trailers) lights evaporative coolers refrigerator and tv. I bonded my centertap neutral of the transformer to ground! This eleminates all mismatch voltages. I ran my oscilloscope and no noise in the signal. So ground the center tap neutral and this stops .This is why i believe your confused.
:( Pity. I bought one of the LVX6048s from watts247 and it's powering most of my house with grid tied but back-feed turned off. I liked that I could use one box to get 120 and 240v. Was also told the transformer would help start my 2.5HP compressor. Wonder if I should consider changing inverters?
No keep it and upgrade when finances allow. Then use that one as additional power capability for a different sub panel.
Exactly, just keep it as extra @@Capoe3
hey how are you doing i am trying to get a control board for my growatt spf 8000t dvm can you help me please thanks
do the LVX6048WP's have the same architecture? about to install 3, to replace EG4 6000EX's.
The lvx6048wp has two separate inverters
@@id007rx Thank You. Again.
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid.
@@bigcbradioI have one system for my whole house.
This inverter
70kwh lithium batteries
Generator interlock that chooses between my solar or grid.
Also have the "grid" connection for the inverter on a plug.
I can choose to plug it into the actual grid or my 12kw diesel military generator.
I don't grid charge because I have a generator.
If the grid goes down and a cloudy winter day.
I can start the generator and use it to charge the batteries and run the house. A full charge with the cloudiest days I can usually go three days.
In the summer with both central air conditioners running (4 tons total) I can go 1.5 days if its hit outside.
Click click
Machine shop radio on the side
I think that's a good catch on what's possible. But its so contrived that I'm confused about your deduction. I've never seen one leg go down to cause this. 240V breakers are linked so that both poles turn off at the same time. If you create this scenario in real life then you should probably stop trying to be an electrician and call in a professional.
Its not entirely about losing one leg. It more about an imbalance between the two legs.
Ok I own one.
I just ran the experiment.
Your missing the point.
Even when u don't loose a leg when in bypass your inverter transformer is trying to balance the neighborhood transformer.
What I just did is this.
I put it in bypass mode without grid charging. With would be the same. But I don't charge from grid ever. Solar charging only.
I took off all load from inverter.
Inverter on
In bypass due to low battery.
I had current on my grid neutral and hots....
So this transformer is balancing in parallel with the pole transformer.
Now being properly breakered for the wire will prevent damage.
My biggest issue is this
now I'm pulling power through my utility meter that I'm not using.
I'm now paying for power my neighbor is using and so is he.
This is absolutely unacceptable!
The point of solar is to reduce my electric bill not pay for my neighbors when my batteries go low and it enters bypass mode.... I'm going to have to isolate the neutral somehow... I'm pissed.
Let me give you a real world example. I have a lvx6048. I had that same exact scenario. I had some bad weather so I decide to use my grid to charge my battery. I lost one leg. The wires that come from the supplier is that black covered aluminum wire that connects at my pothead that is joined to copper wire. Copper and aluminum does not like each other. About 4am I got an error code on my inverter. It was very quiet so I could hear the arcing noise on the roof. I went up there and the aluminum was turning to dust with intermittent electrical contact. It cost me my main board in my inverter that I have since replaced. So that how you lose a leg. Better safe than sorry
@@bigcbradio You maybe right but that job was done by so called professionals. But that's apart of life and thats why we have things like reverse polarity protection and a ton of other protection that most times trigger by human error. So where is the protection for this one. Its clearly designed flaw one that I would prefer to avoid.
@@bigcbradio safe is when something goes wrong a protection circuit kicks in. Safe is when a gfci switch shuts down when water gets into it. You could argue that not having water near it is safe. This house was connected more than 18 years to the grid.
It appears the only problem here is connecting the neutral of the input to the neutral of the output. The input shouldn't have a neutral connection at all.
Phase. You keep using that word. I do not think it means what you think it means.
is auto Transformer the regular term?
I ask because english is not my native language!
where i live we have 3 phases...
so please do not misunderstand !
thank you for this video!
You do not need to worry about this unless you live in a country with 120V electrical outlets. If you have for example 240/400V you will not have this autotransformer inside your inverter.
Autotransformer is a proper term. While most transformers have two separate windings (and some have more than two), an autotransformer has a single winding. In English, the term "auto" means self, or a single unit. As usual, there is a connection to each end of the winding, also there will be one or more "tap" connections to the winding. If you had a winding with a tap in the center, the voltage between the tap and either end of the winding would be half the voltage. The tap could be placed at any point along the winding to get any voltage. Since there is only one winding, there is a savings in the cost of the wire and the size of the transformer. The disadvantage is that the input and output are not electrically isolated as they would be if there were two separate windings.
Autotransformer does not have an isolation between its primary and secondary, and its primary and secondary winding are partly shared.
If this is not a low frequency inverter then what is,i respect your intelligence sir but i disagree when you say transformer based inverters are high frequency
The issue is that unless you have a switched neutral that is isolated you’re always ys going to have what you’re describing if grid connected when it goes into pas through. Doesn’t matter the design. If it is a low frequency unit it will always have this and so will an auto inverter.
The only real solution is to use an isolated charger to charge batteries and never go to grid but that’s at best 94% efficient and thus expensive. You could make it better if instead of stepping down went to the 400vdc bus voltage and reinverted instead of battery voltage.
Of course this goes back to the con job done to Congress in the 1930s making everyone’s homes unsafe to save power companies a little money: transformers on the poles should be isolated and the isolated side center tapped. Then there’s never an issue.
Bypass mode AND charging.... What about if you don't charge from grid? I only charge from solar. It will bypass when batteries get low but not charge. That defeats the purpose of solar in my opinion to charge from grid.
@@electromechanicalstuff2602 the issue is that the auto transformer when you go into grid bypass will then balance the grid itself because the grid doesn’t use isolated transformers. So you become your neighbor’s neutral balancing.
That will cook the auto transformer because it’s everyone on your phase to the sub station net/net.
If the grid was done properly instead of how Congress allowed them to get away with this wouldn’t be an issue because every house would have an isolated transformer and the secondary would be center tapped. But because cronyism and cost cutting we get lightening strikes and stupid isolation rules that drive cost up and net efficiency way down while still being less safe. The power companies just like it because the efficiency is after the meter not before.
If you’re using grid charging and it stays on inverter you won’t have this issue because any UL listed box will have isolation for that grid charge thus protecting you from the imbalance.
The fundamental problem is that unless there’s a relay after the low frequency transformer in a center tapped inverter the same thing will happen there too because it’s still connected to the grid neutral in bypass mode so the center tap effectively is an auto transformer at that point.
And of course an high frequency transformer less design with out of phase dual inverters for generating 120+120 is getting the fets hammered if the neutral is out of balance in bypass mode.
So there’s way more to this than just the auto transformer.
That said, I don’t use my grid’s neutral at all even in bypass and the auto transformer has never seen more than 12 amps on it (I have an arduino with clamps monitoring it so I know if there is any risk and I need a second one)
@@jameshancock why is he specifically calling out when charging?
@@jameshancock I understand that my transformer and the pole transformer are essentially working in parallel causing my transformer to become the load balancer. I only have a 50 amp breaker on my inverter because I never allow grid charging and so far no tripping. Doesn't mean it's not happening but I'm going to experiment and see for myself. Because if in the times I'm on bypass my meter is measuring power I'm not using to balance the neighbors house I may have to look into maybe installing a 3 phase transfer switch so I can disconnect the neutral from grid to my critical loads panel
@@electromechanicalstuff2602 that’s not how I interpreted it. I interpreted it as when in bypass from grid directly to house.
You don't have clue what you're talking about. If you connect a scope or a frequency meter at the output of the FET board or the primary windings at the transformer, you'll measure 60 or 50 Hz. Besides, if what you say is true then where are the high frequency transformers, and high voltage caps and high voltage diodes in this inverter? There are none.
Can you recommend a good hybrid 240v single phase?
99% of the split phase inverters in the world are transformer based. They are robust and can absorb large inrush currents. Your concerns are baseless.
I own one of these. I'm not worried because I don't charge from grid.... Y would u. When my batteries die I bypass to grid but don't charge from. This prevents the transformer relay from ever being engaged in the first place. When the solar recharged my batteries it switches back to invert mode. But what he says is accurate ish. Regardless of loosing a leg or not . If you have a large imbalance from L1-L2 the transformer inside the inverter will be working in parallel to the pole transformer to balance the load. More or less
Ok I own one.
I just ran the experiment.
Your missing the point.
Even when u don't loose a leg when in bypass your inverter transformer is trying to balance the neighborhood transformer.
What I just did is this.
I put it in bypass mode without grid charging. With would be the same. But I don't charge from grid ever. Solar charging only.
I took off all load from inverter.
Inverter on
In bypass due to low battery.
I had current on my grid neutral and hots....
So this transformer is balancing in parallel with the pole transformer.
Now being properly breakered for the wire will prevent damage.
My biggest issue is this
now I'm pulling power through my utility meter that I'm not using.
I'm now paying for power my neighbor is using and so is he.
This is absolutely unacceptable!
The point of solar is to reduce my electric bill not pay for my neighbors when my batteries go low and it enters bypass mode.... I'm going to have to isolate the neutral somehow... I'm pissed.
Wow....I see Many. Man Made Problem = Don't Do What He Said 17 years xw 4860 x3 = 18kw I S/W The Neutral Too
Thank You , Take Care & Have Good Day