I have installed the inverter, in the Cape, by providing the feed to the inverter before the Earth Leakage on the DB and everything worked.

I moved the inverter to Pretoria and added a 15A plug to the supply side to use it as a temporary backup system until the wiring can be changed. When I switch the inverter on, it starts but after a period it trips the earth leakage on the main DB. No load is attached to the inverter and the battery is also disabled. Somewhere I saw a diagram that the inverter supply is always taken before the earth leakage on the DB.

It runs from the battery. I have set 10 (Operating logic) to "ON" Line Mode and 23(bypass function) to byF to prevent it from operating in bypass/ECO mode. The moment I plug the inverter into a the Eskom supply socket it trips the earth leakage.

I have removed the earth from the supply side and now it is not tripping the earth leakage. I know this is not safe but are adding an earth leakage to the outgoing side of the inverter. The system can now be used as a standalone system, like a generator, without changing the DB. The endurance and capacity are more than a UPS and this might be a solution for people renting apartments where generators can't be used. 

Hello JohannFer

I am new to this forum and am trying to get advice here too.

I have an Axpert MKS 4 and I have the same issue with it tripping the earth leakage device in the incoming consumer unit. I have been in contact with a chap in the UK and he advised me that the Axpert has a N to E connection inside of the box as opposed to some that you make this connection outside of the inverter. This therefore makes a second N to E connection inside the property which is not allowed, it seems that this is a factor in the tripping issue.

I am not an electrician and I do have a limited knowledge of the issues surrounding inverters. I am looking at a number of ways to get round the tripping issue including a purpose made grounding box that is available to fit I assume before the connection to the inverter AC input.

If I hear of any other options I will drop you a reply if they are relevant to your issue

Regards  Bony999

Edited February 27, 20233 yr by bony999

1 hour ago, bony999 said:

Hello JohannFer

I am new to this forum and am trying to get advice here too.

I have an Axpert MKS 4 and I have the same issue with it tripping the earth leakage device in the incoming consumer unit. I have been in contact with a chap in the UK and he advised me that the Axpert has a N to E connection inside of the box as opposed to some that you make this connection outside of the inverter. This therefore makes a second N to E connection inside the property which is not allowed, it seems that this is a factor in the tripping issue.

I am not an electrician and I do have a limited knowledge of the issues surrounding inverters. I am looking at a number of ways to get round the tripping issue including a purpose made grounding box that is available to fit I assume before the connection to the inverter AC input.

If I hear of any other options I will drop you a reply if they are relevant to your issue

Regards  Bony999

Yes , The MKS4 has its own built-in bonding relay , which automatically disconnects from input neutral , and bonds the output neutral to earth when the grid input falls away. So please do not use an external bonding arrangement. 

As it is a temporary installation and the inverter is plugged into an outlet socket, I removed the ground from the input to the inverter, With the permanent installation the supply to the inverter will be taken before the earth leakage in the DB and a new earth leakage will added be on the output side of the inverter.

Proposed installation for stand-alone system. Don't connect the input earth to the input to the inverter but add an RCB on the output for protection

Hello BritishRacingGreen

Thanks for the reply and forgive my lack of knowledge, but does this mean then that with the ac connected to the inverter the via all input protections etc that when the ac is not supplying power to the inverter but the inverter is supplying power to the output side of the inverter, the earth connection is maintained between the consumer unit in the house and the output of the inverter via the earth from the ac input?

If so is this the reason that the earth leakage is detected by the leakage device in the consumer unit in the house when the relay swaps over from input to output neutral?

 

regards and thanks

Bony999

1 hour ago, bony999 said:

Hello BritishRacingGreen

Thanks for the reply and forgive my lack of knowledge, but does this mean then that with the ac connected to the inverter the via all input protections etc that when the ac is not supplying power to the inverter but the inverter is supplying power to the output side of the inverter, the earth connection is maintained between the consumer unit in the house and the output of the inverter via the earth from the ac input?

If so is this the reason that the earth leakage is detected by the leakage device in the consumer unit in the house when the relay swaps over from input to output neutral?

 

regards and thanks

Bony999

The answer is best serve at the hand of a simple schematic, which I will draft tommorrow morning for you. 

10 minutes ago, BritishRacingGreen said:

The answer is best serve at the hand of a simple schematic, which I will draft tommorrow morning for you. 

It would be interesting to see the complete circuit. What is interesting as an electrical guy and agreeing on the reasons for taking the input before the E/L. 

My 24V Axpert is also fed from a 3 pin socket and just wonder why my inverter does not trip the E/L if the output is not connected to the DB but also fed my own multiplug made up of 4xdouble sockets. 

This is how I used it when I got it. Later I connected the whole house to the output via a transfer switch. Again no problems with a E/L. 

Hi @bony999 , @Scorp007 the schematic diagram below refers:

1. please not that the inverter input ac circuit may be connected before the Existing main DB Board ELD . In my case it is wired after the ELD . It can be argued that the inverter circuit is a fixed appliance , and input ELD protection may or may not be required.

2. The inverter has two fundamental modes , Line Mode and Battery mode. In Line mode the RLY1 and RLY3 relay  normally open contacts are made and as you can see as a reslt , the Eskom neatral is passed thru to the inverter to the loads. Because the input grid is on , the assurance is there that the neatral is earth bonded from the residential connection as shown on the left of the diagram.

3. When the grid fails , the inverter is in Battery mode . No assumption can be made that the grid neatral at the inverter is bonded to earth anymore . It must also be taken into account that CB1,ELD1 ,CB2 and ISO1 can also be disconnected due to ELD trips or overload , and because these devices are double-cut , the bonded neatral is not available anymore.

 

4. for reasons in (3) , the inverter must now reconstruct the neutral with its own bond to earth , so that the inverter load circuits can function within requirements. To do so the input grid is isolated by means of RLY3 and RLY1 de-energizing , and at the same time the output neutral is bonded to earth via the normally closed contact of RLY1. We have now formed an island which is divorced from the Eskom grid , and the load ELD can now still function correctly via the island bond of earth to neutral.

5. When Eskom grid becomes available again , the RLY3 and RLY1 is energized again , the island earth bond is removed and the Eskom neutral is again passed thru to the loads.

 

EDIT : an argument can be made why it is not possible to just introduce a permanent  bond at the inverter. The reason is COC does not allow us to have more than one bond on a residential neutral , and as a lesser reason , the ELD1 , if introduced as per above diagram , will trip due the downstream bond . And this is also the reason why a trolley backup inverter will trip the Main ELD via a plug input, if the inverter does not have a proper bonding and disconnection arrangement as above circuit. 

 

 

Edited March 7, 20233 yr by BritishRacingGreen

I have the solution: install a constant voltage transformer to create an isolated secondary from the earth leakage outlet.

Above solution may be a bit expensive. Another option someone can try is to rectify the a.c. and connect it to the PV input (tripping, failure, arcs and fire is possible).

Hello BrisishRacingGreen

Thanks very much for the drawing and the explanation to go with it. It is very informative and makes perfect sense. I have the Axpert MKS4 5 kw inverter as part of a pre build cabinet and it has C plugs on the unit by which to connect the input AC and the output AC to the solar consumer unit. The solar output is completely separate from all other sockets in the home and is never supplied from the grid when it is in AC charging mode for the batteries overnight. The ac output is disconnected/isolated when the inverter is using overnight electricity.

The question remains as to how the ac load side of the system obtains an earth when the input ac is disconnected? Does this setup require some device on the output side of the inverter to switch to an earth for the ac output consumer unit? Currently the earth is via the supply line and socket but when the socket is removed so is the earth. 

The system is still to be completed and is not being used as yet but once I have ironed out the issues I am having I want it to be correct.

The cabinet is designed to be able to use a backup generator or the grid to charge the batteries overnight and so far it makes more sense if it is a generator but less if it is the grid.

Many thanks for taking the time to do such a detailed drawing and excuse my lack of knowledge.

Regards Bony999

 

Edited March 9, 20233 yr by bony999
missed some out