Wiring in 2000w inverter

[VicS]

It was a question.

If its a centre tapped earth , or even a pseudo centre tapped earth, there is no neutral but two "lives" each 115 volt with respect to the earth connection

These inverters are too compact and and far too light to contain a 230 volt, 2kVA output transformer with a genuine centre tapped secondary winding like a site transformer. Hence my term "pseudo centre tapped" although we do not know exactly how that is done. Perhaps Matthew can find the time to "reverse engineer" the now defective one he used for his videos

 

[PaulRainbow]

If its a centre tapped earth , or even a pseudo centre tapped earth, there is no neutral but two "lives" each 115 volt with respect to the earth connection

These inverters are too compact and and far too light to contain a 230 volt, 2kVA output transformer with a genuine centre tapped secondary winding like a site transformer. Hence my term "pseudo centre tapped" although we do not know exactly how that is done. Perhaps Matthew can find the time to "reverse engineer" the now defective one he used for his videos

The point is, what is the E terminal of the inverter socket connected to. Is it just the case, or is it connected internally to the inverter. Not a hard question.

 

[rogerthebodger]

If its a centre tapped earth , or even a pseudo centre tapped earth, there is no neutral but two "lives" each 115 volt with respect to the earth connection

These inverters are too compact and and far too light to contain a 230 volt, 2kVA output transformer with a genuine centre tapped secondary winding like a site transformer. Hence my term " pseudo centre tapped" although we do not know exactly how that is done. Perhaps Matthew can find the time to "reverse engineer" the now defective one he used for his videos

That confused me as matthew reported a voltage between L / E and a different lolage N / E I also considered it to be some kind of centre tap or as you called it pseudo centre tapped.

The real question is how for you include a RCD in the system if it is an installed inverter rather than a portable.

To me the issue is using metal cased appliances where a short could send a shock through the user a earth wire/yellow/green connected back to the supply neutral would cause an imbalance even before the user had contact with the case to trip the RCD.

 

[VicS]

That confused me as matthew reported a voltage between L / E and a different lolage N / E I also considered it to be some kind of centre tap or as you called it pseudo centre tapped.

The real question is how for you include a RCD in the system if it is an installed inverter rather than a portable.

To me the issue is using metal cased appliances where a short could send a shock through the user a earth wire/yellow/green connected back to the supply neutral would cause an imbalance even before the user had contact with the case to trip the RCD.

The difference between the L/E and N/E voltages is not great enough to be significant. It is within the tolerances you might expect for the components used to create the pseudo centre tap.

What rang alarm bells in my mind when Matthew first posted the video was that together they fell well short of the L/N voltage ! 100 + 96 is a long way short of 226. I don't understand that.

If you are going to use an RCD the inverter output should have an earthed neutral, not be centre tapped. If the inverter is plumbed in to the boat's shore power system ( via a transfer switch ) I guess it could have is own RCD or perhaps be connected in upstream of the shorepower RCD ??

 

[VicS]

The point is, what is the E terminal of the inverter socket connected to. Is it just the case, or is it connected internally to the inverter. Not a hard question.

Why are you asking that ?
you said that Durite had told you that the case ground terminal is connected to the ground terminal in the ac outlet socket.

 

[PaulRainbow]

If you are going to use an RCD the inverter output should have an earthed neutral, not be centre tapped.

I've been repeatedly saying this since post #66

An inverter that is connected to the AC systems is an "installed" inverter and is governed by the same rules as any other AC source (shore power and genset). As far as i am concerned, the only inverters that should be used in an installation are those that can be connected Neutral to Earth, that applies equally to an installed generator. All installed sources should have N-E bonded at source (shore power at the marina, genset at the genset and inverter at the inverter). All sources should be connected to a changeover device that only allows one source to be used at a time and it should be break before make.

If the inverter is plumbed in to the boat's shore power system ( via a transfer switch ) I guess it could have is own RCD or perhaps be connected in upstream of the shorepower RCD ??

If the inverter is installed it has to be via a changeover switch, power therefore goes to the onboard AC system in the same way that shore power does, it normally does not need additional RCDs.

 

[PaulRainbow]

Why are you asking that ?

Because i would like to know, do you have an answer ?

you said that Durite had told you that the case ground terminal is connected to the ground terminal in the ac outlet socket.

Yes, but that's not what i asked here.

 

[Lon nan Gruagach]

That confused me as matthew reported a voltage between L / E and a different lolage N / E I also considered it to be some kind of centre tap or as you called it pseudo centre tapped.

The difference between the L/E and N/E voltages is not great enough to be significant. It is within the tolerances you might expect for the components used to create the pseudo centre tap.

What rang alarm bells in my mind when Matthew first posted the video was that together they fell well short of the L/N voltage ! 100 + 96 is a long way short of 226. I don't understand that.

What would have helped is concurrent measurement of L-N, L-E and N-E. I am confident that that would reinforce your statement about component tolerance where a virtual Earth exists. By including various (small) loads you might also determine the effective centre tap to E impedance , something of great importance.

 

[VicS]

The point is, what is the E terminal of the inverter socket connected to. Is it just the case, or is it connected internally to the inverter. Not a hard question.

.............. you said that Durite had told you that the case ground terminal is connected to the ground terminal in the ac outlet socket.

Yes, but that's not what i asked here.

You also said that Durite told you the earth pin was "centre tied"

If these two facts do not tell what you want to know you did not ask Durite the right questions.

 

[PaulRainbow]

You also said that Durite told you the earth pin was "centre tied"

If these two facts do not tell what you want to know you did not ask Durite the right questions.

Do you have anything useful to add ?

Do you know where the "E" pin is connected to, other than the case ?

Do you know if the inverter is centre tapped or "pseudo" centre tapped ?

Are you just trolling to cause an argument ?


I suspect the answers to the above are all "no", except for the last one.

 

[rogerthebodger]

Do you have anything useful to add ?

Do you know where the "E" pin is connected to, other than the case ?

Do you know if the inverter is centre tapped or "pseudo" centre tapped ?

Are you just trolling to cause an argument ?


I suspect the answers to the above are all "no", except for the last one.

Paul Vic and I are just trying to find all the details so we and analysis the info and come to a technical conclusion as to what is required to use of this type of inverter.

 

[PaulRainbow]

Paul Vic and I are just trying to find all the details so we and analysis the info and come to a technical conclusion as to what is required to use of this type of inverter.

You and i are trying to find the details, If Matthew could confirm where the "E" terminal is internally connected it would definitively determine whether the inverter is centre tapped or not.

It is either centre tapped, which should have the "E" pin connected to the centre tap, or it is not centre tapped, should should have the "E" pin connected to "N".

If it was some shoddy junk it might not be connected to anything, i very much doubt that would be the case with a Durite inverter.

Vic is just trolling.

 

[rogerthebodger]

You and i are trying to find the details, If Matthew could confirm where the "E" terminal is internally connected it would definitively determine whether the inverter is centre tapped or not.

It is either centre tapped, which should have the "E" pin connected to the centre tap, or it is not centre tapped, should should have the "E" pin connected to "N".

If it was some shoddy junk it might not be connected to anything, i very much doubt that would be the case with a Durite inverter.

Vic is just trolling.

I agree we do need more information as to the internal connections.


Having meet Vic I don't agree I have found to be a perfect gentleman.

 

[Graham376]

If you are going to use an RCD the inverter output should have an earthed neutral, not be centre tapped. If the inverter is plumbed in to the boat's shore power system ( via a transfer switch ) I guess it could have is own RCD or perhaps be connected in upstream of the shorepower RCD ??

I had problems with an inverter with an earthed neutral. A few years ago, as a quick temporary fix, I plugged a cheap inverter into one of the boat's sockets, to get 240v to all. Obviously, this by passed the rcd, being downstream of it. Went on to a pontoon (Alcoutim), plugged into shore power and the pontoon rcd tripped, mine didn't. Lots of head scratching and checking shore lead etc. but couldn't find anything wrong. Eventually, a forumite, Paul D, asked if anything new had been fitted - the inverter. Turned out the inverter had an earthed neutral and although it was switched off, it was still plugged in and that was causing the fault. Unplugged, fault went away. New Sterling inverter fitted, no problems. Later wired in properly via changeover switch.

 

[Lon nan Gruagach]

I had problems with an inverter with an earthed neutral. A few years ago, as a quick temporary fix, I plugged a cheap inverter into one of the boat's sockets, to get 240v to all. Obviously, this by passed the rcd, being downstream of it. Went on to a pontoon (Alcoutim), plugged into shore power and the pontoon rcd tripped, mine didn't. Lots of head scratching and checking shore lead etc. but couldn't find anything wrong. Eventually, a forumite, Paul D, asked if anything new had been fitted - the inverter. Turned out the inverter had an earthed neutral and although it was switched off, it was still plugged in and that was causing the fault. Unplugged, fault went away. New Sterling inverter fitted, no problems. Later wired in properly via changeover switch.

As has been mentioned a few times here, it is important to use a 2 pole, break before make switch to select your 240V ac source...
What was happening with the cheap inverter was that you were connection pontoon Neutral to Pontoon Earth. All Neutral return currents for the entire pontoon (probably) were then split between the pontoon Neutral and your pontoon Earth. Current will have flowed out of the pontoon Neutral, through its RCD, through your Neutral - Earth link (in the inverter), back to the sub-station N-E link and finally to the transformer.
Not a pretty situation, saved only by long runs of cable, otherwise you will have experienced a significant fault current.

edit add:
Bold bit
So you admit to having made a live 13A plug with live mains on the exposed pins...

 

[Graham376]

As has been mentioned a few times here, it is important to use a 2 pole, break before make switch to select your 240V ac source..........

So you admit to having made a live 13A plug with live mains on the exposed pins...

Well aware of the switch, I mentioned it in #5.

No live pins as they were both plugged in when in use, when not, obviously important to remove both not just one. As I mentioned previously, it was a temporary lash-up for when on mooring.

 

[superheat6k]

As has been mentioned a few times here, it is important to use a 2 pole, break before make switch to select your 240V ac source...
What was happening with the cheap inverter was that you were connection pontoon Neutral to Pontoon Earth. All Neutral return currents for the entire pontoon (probably) were then split between the pontoon Neutral and your pontoon Earth. Current will have flowed out of the pontoon Neutral, through its RCD, through your Neutral - Earth link (in the inverter), back to the sub-station N-E link and finally to the transformer.
Not a pretty situation, saved only by long runs of cable, otherwise you will have experienced a significant fault current.

edit add:
Bold bit
So you admit to having made a live 13A plug with live mains on the exposed pins...

Extremely fortunate for the poster here that the Inverter was just plugged in, but not on and so not powering the AC system at the time the external shore power was plugged in. AC power supplies connected out of phase do not take prisoners. A 16a shore power plug exploding in your hand is not a pleasant experience !

 

[matthewriches]

Will try and get some pics up later but the case is connected to the AC earth in and also to the main PCB so there is some sort of centre tapping arrangement going on, confirmed on the Durite inverter that I looked at.

 

[PaulRainbow]

Will try and get some pics up later but the case is connected to the AC earth in and also to the main PCB so there is some sort of centre tapping arrangement going on, confirmed on the Durite inverter that I looked at.

No doubt that accounts for the Durite claim that the inverter would shut down faster than a RCD, in which case it didn't need one.

 

[matthewriches]

For an installation, which is where the video originally stemmed from?

in which case it didn't need one.