Signature Solar's new EG4 6000 120/240V inverter

[FilterGuy]

If I understand the test correctly, I need to hook up incoming AC power, but have batteries and solar off, and then a single 120V load connected? Then you want to see what the current is on the incoming neutral?

How could I not have current on the neutral with a single output? Are you saying that the inverter might actually be using the incoming ground as the output neutral because they are internally bonded? [and it's expecting that it's the source of all downstream power, so a bonded ground and neutral is no problem?]

If the output neutral is independently derived through the center tap of the output transformer, the Current on the output neutral would not show up on the input neutral. It would only show up as a load on the 240V.

In this test, do you want both incoming hots, the ground, and the neutral all connected?

Yes

 

[thanhrodke]

If the output neutral is independently derived through the center tap of the output transformer, the Current on the output neutral would not show up on the input neutral. It would only show up as a load on the 240V.


Yes

[see next post]

If you read this, is there a way to delete a post?

 

[thanhrodke]

If the output neutral is independently derived through the center tap of the output transformer, the Current on the output neutral would not show up on the input neutral. It would only show up as a load on the 240V.

We have confirmed that there is no current on the input neutral when there was about a 100 watt load on the unit in passthrough mode. That was an 8 ft LED shop light.

We also tested the inverter with the ground disconnected and it runs fine, with the neutral disconnected and it runs fine, and with both the ground and neutral disconnected and it still runs fine. In all cases listed in this paragraph, the shop light worked with no issues.

So the unit will run without issue on just the two incoming AC feeds. To clarify, it will run with no ground and no neutral hooked up and still produce an outbound neutral. So that means it has to be using the center tap on the transformer to produce that neutral. Just for my learning, is the system shifting the other hot phase 180° in order to produce this neutral or just gathering it while the phases are crossing at zero volts? (I'm on the other end of electronics knowledge compared to you and @Subdood).

I don't remember where it was discussed, but we also attempted to power up the inverter with just one of the incoming grid phases connected (both ground and neutral connected) and it would not power up with either one of them alone.

It absolutely takes both phases to power the unit up, and based upon the fact that it will run totally fine with nothing but the two hots hooked up, as in no ground and no neutral inbound, then it must be using a center tap transformer to produce the output neutral.

 

[OzSolar]

@thanhrodke Your topic directly above is where everyone needs to really think about when getting into solar/inverters. You're going to be adding a good amount of $ in batteries in order to maintain the idle consumption of these inverters. If one spends a little more on a better UL inverter upfront like a Scheider or Outback the idle consumption is MUCH lower. A pair of Conext 6048s has a idle consumption of 16w (8watts each per spec sheet).
View attachment 111078

Timely post. I'm trying to get to bottom of this for an inverter choice right now. I will offer that "Sleep mode" usage is a different animal than "no load idle mode" so I don't think it's fair to compare the two. Most people aren't going to be able to use sleep mode without it wreaking havoc on sensitive electronics and just plain being a hassle in anything other than that smallest of applications.

Still what little I can find on the Schneider type of inverters puts their no load idle at less than 30 watts.

 

[thanhrodke]

Correction: about the time I was messing with the grounds, we had cloud cover. Lights still flicker when there's lots of solar power coming in, say 4,000-5,000 watts or more.

Random: not sure what's changed, but I've got no light flicker or rattling noise on my left inverter today. Possibly related to how far I pulled pulled open the front cover. Maybe the sheet metal is under enough stress to stop the rattle, or I moved the right wire just far enough to stop the vibration. Whatever the cause, no rattle and no light flickering today.

 

[thanhrodke]

Timely post. I'm trying to get to bottom of this for an inverter choice right now. I will offer that "Sleep mode" usage is a different animal than "no load idle mode" so I don't think it's fair to compare the two. Most people aren't going to be able to use sleep mode without it wreaking havoc on sensitive electronics and just plain being a hassle in anything other than that smallest of applications.

Still what little I can find on the Schneider type of inverters puts their no load idle at less than 30 watts.

I'll try to get tome better numbers on these new EG4 6000 units. my only number has come from solar assistant was showing, but I don't know how accurate that is. I'll get my shelly EM units hooked up over there for testing and disconnect all output. I will then test the load when on grid only, when on solar, and when on power. might be able to do this tonight.

 

[FilterGuy]

We have confirmed that there is no current on the input neutral when there was about a 100 watt load on the unit in passthrough mode. That was an 8 ft LED shop light.

We also tested the inverter with the ground disconnected and it runs fine, with the neutral disconnected and it runs fine, and with both the ground and neutral disconnected and it still runs fine. In all cases listed in this paragraph, the shop light worked with no issues.

So the unit will run without issue on just the two incoming AC feeds. To clarify, it will run with no ground and no neutral hooked up and still produce an outbound neutral. So that means it has to be using the center tap on the transformer to produce that neutral. Just for my learning, is the system shifting the other hot phase 180° in order to produce this neutral or just gathering it while the phases are crossing at zero volts? (I'm on the other end of electronics knowledge compared to you and @Subdood).

I don't remember where it was discussed, but we also attempted to power up the inverter with just one of the incoming grid phases connected (both ground and neutral connected) and it would not power up with either one of them alone.

It absolutely takes both phases to power the unit up, and based upon the fact that it will run totally fine with nothing but the two hots hooked up, as in no ground and no neutral inbound, then it must be using a center tap transformer to produce the output neutral.

Hmm.... I just realized the test I asked you to do may not completely prove the neutral is independently derived. The test does prove that the output transformer is hooked up and active while in passthrough mode. Therefore if the input neutral is disconnected, the center tap of the transformer would provide neutral. However, if we look at model 1 (See post 55), we can see that even if the input neutral is connected to the output neutral in pass-through mode, the center tap of the output transformer would still be involved. Because the center tap of the output transformer is still involved. The current on the input neutral would not the same as the load current.

A 100W load would create about .8 amp. As a first approximation, about half of that would be handled by the center tap.... but that estimate could be way off in either direction. Consequently, the measured current on the input current could be really small. It would be interesting to do the same test with a much larger load and see if there is current on the input neutral.

 

[summit]

OK. That tells us it is not a common neutral architecture. (No surprise)




On all inverters I have ever seen, In-ground, Out-ground and case are all tied together.... so no surprise there.

It looks like the output neutral has a permanent N-G bond or it is a dynamic N-G bond (It depends on whether the Neutral is switched). This is fine for a single inverter, but if you have more than one inverter it creates multiple N-G bonds. I wonder if there is a way to disable the N-G bond on one of the inverters.

View attachment 111326


On all inverters whit dynamic bonding, the relay's "normal" position is inverter mode so when the system is totally unhooked you should see the bond through the bonding relay.


View attachment 111327


To determine if it is an independently derived neutral, put a single 120V load on the output while in passthrough mode. If you don't see a current on the input neutral that is about the same as the load current, it is probably not an independently derived neutral.

Do the EG4 6000EX-48 already have an ATS built-in as drawn ? thanks

 

[FilterGuy]

Do the EG4 6000EX-48 already have an ATS built-in as drawn ? thanks

Yes...... but we are trying to figure out if they switch neutral or if they just create an independent neutral on the output.

 

[thanhrodke]

Hmm.... I just realized the test I asked you to do may not completely prove the neutral is independently derived. The test does prove that the output transformer is hooked up and active while in passthrough mode. Therefore if the input neutral is disconnected, the center tap of the transformer would provide neutral. However, if we look at model 1 (See post 55), we can see that even if the input neutral is connected to the output neutral in pass-through mode, the center tap of the output transformer would still be involved. Because the center tap of the output transformer is still involved. The current on the input neutral would not the same as the load current.

A 100W load would create about .8 amp. As a first approximation, about half of that would be handled by the center tap.... but that estimate could be way off in either direction. Consequently, the measured current on the input current could be really small. It would be interesting to do the same test with a much larger load and see if there is current on the input neutral.

does it help that the amperage test was done through a klein multimeter, and not an inductive pickup? I was using the 10A direct measurement on the multimeter. I am assuming that was a quite accurate measurement.

since it was a known low load, I connected the hot to the LED plud narrow blade, but I had the inverter out neutral just hanging in the air, and connected the klein multimeter between the out neutral and the neutral (wide) blade on the LED shop light cord. To word it another way, the klein itself was completing the circuit, and directly measuring that circuit.

it was drawing about .8 amps for a light fixture rated at 72 watts, but they draw a little more than that.

 

[thanhrodke]

Yes...... but we are trying to figure out if they switch neutral or if they just create an independent neutral on the output.

I will say that when powered by the grid, the 'hit' when engaging the output transformer is solid. there is a very distinct audible thump and case rattle when it engages the output. but with the solar or battery input, it's a much 'gentler' ramp up over what seems to be 1-2 seconds.

on grid power, that engagement is like banging your fist on a desk.

 

[FilterGuy]

does it help that the amperage test was done through a klein multimeter, and not an inductive pickup?

yes

 

[thanhrodke]

@FilterGuy, so does that give you enough data to declare it an independently derived neutral, or is further testing needed?

I can rewire it again, and do a test with a heavier load.

but the fact that the unit will run loads in passthrough mode when there is NO input neutral, doesn't that mean that it's a derived neutral?

 

[summit]

how many wires are connecting to the transformer ? if it's within view. Five wires for an isolating and 3-wire for an auto-transformer.

 

[FilterGuy]

it was drawing about .8 amps for a light fixture rated at 72 watts, but they draw a little more than that.

Is that .8A on the output neutral and was the measured current on the input actually zero? That would sure indicate it is a derived neutral.

 

[FilterGuy]

how many wires are connecting to the transformer ? if it's within view. Five wires for an isolating and 3-wire for an auto-transformer.

I am 99% sure that when in passthrough mode the transformer is operating as an auto-transformer. I am 90% sure that the transformer *does* have a secondary and primary winding. When in invert mode, the transformer is operating as an isolation step-up transformer. (See the models in post #55)

 

[FilterGuy]

@FilterGuy, so does that give you enough data to declare it an independently derived neutral, or is further testing needed?

I can rewire it again, and do a test with a heavier load.

but the fact that the unit will run loads in passthrough mode when there is NO input neutral, doesn't that mean that it's a derived neutral?

I can't say definitively, but all indications are that Neutral is NOT passed through in pass-through mode. It appears that it is a derived neutral in passthrough mode.

I have been trying to think of a test that would be 100% conclusive, but I have not been able to. (There is probably an obvious one that I am just not realizing). A huge 120V load on the output and measurement of zero current on the input neutral would be a lot more conclusive, but even that is not 100%

 

[FilterGuy]

I will say that when powered by the grid, the 'hit' when engaging the output transformer is solid. there is a very distinct audible thump and case rattle when it engages the output. but with the solar or battery input, it's a much 'gentler' ramp up over what seems to be 1-2 seconds.

on grid power, that engagement is like banging your fist on a desk.

The internal transfer switch engages some very hefty relays/contactors when switching from grid to inverter. With this size inverter, the relays are going to have to be pretty large so it is not a surprise that you get a big 'thunk' when they engage.

 

[John Frum]

I can't say definitively, but all indications are that Neutral is NOT passed through in pass-through mode. It appears that it is a derived neutral in passthrough mode.

I have been trying to think of a test that would be 100% conclusive, but I have not been able to. (There is probably an obvious one that I am just not realizing). A huge 120V load on the output and measurement of zero current on the input neutral would be a lot more conclusive, but even that is not 100%

What about interrupting the upstream neutral?
If you can can run a 120VAC load downstream and get current flow on the downstream neutral that would be informative, right?
I've come in the middle of this and may well be totally out to lunch.

 

[FilterGuy]

What about interrupting the upstream neutral?
If you can can run a 120VAC load downstream and get current flow on the downstream neutral that would be informative, right?
I've come in the middle of this and may well be totally out to lunch.

@thanhrodke has already confirmed that the 120V output works fine in pass-through mode with the input neutral disconnected..... But that does not tell us a lot more than we already know.

I am pretty sure (Almost positive) the inverter feeds the primary of a transformer with a center tap on the secondary to create a neutral.
I am also pretty sure (Almost positive) that when in passthrough mode, the 240V AC-in hots are connected to the 'outer' leads of the secondary of the transformer.

What I don't know for sure is whether the input neutral is connected to the output neutral (and center tap) when in pass-through mode.

Let's assume the inverter does connect the input and output neutrals in passthrough mode. In this case, the output transformer would act as an autotransformer with the neutral from the grid tied to the center tap of the output transformer. In this situation, at least some of the neutral current from the 120V load would be handled by the autotransformer (But I don't know how much). If the input neutral is completely disconnected, the transformer would act as an auto-transformer and handle all the neutral current of the 120V load.