Jump to content

Axpert 5KVA MKS inverter installation planning


viper_za
 Share

Recommended Posts

Hi all

 

Let me just start with that my field that I work in is IT and for this I'm just trying to get an understanding of how things will fit together.

My goal is to get all the wiring and breakers etc installed before I get the electrician to do the main AC connections.

 

I have already purchased my first string of panels 3x 300W ReneSola Virtus II and the inverter itself.

 

First off my inverter will not be installed next to the current DB as this is located in my passage between 2 bedrooms.

This will be installed +-10-15m away with the battery bank next to it.

The DB will be split with the stove and geyser not going through the inverter.

 

Can you please have a look at my wiring diagram just to confirm that I am indeed on the right track with my planning.

post-947-0-31932000-1438842289_thumb.jpg

You will see that I gave the existing Breakers and bus bars a grey background and the new ones a white one.

My current DB only has a E/L that functions as a main and I will be installing a new Mains breaker to be able to supply the inverter with "clean" power.

 

The thing I am really not 100% sure about is the neutral to earth bonding on the output side of the inverter.

I am also not sure about what size the cables should be running to and from the input and output of the inverter into the house.

The same goes for the earth cable size.

 

Any suggestions are welcome.
Thanks
Thys

 

 

Link to comment
Share on other sites

Hi Thys

 

To me your diagram looks good. You neutral - earth bonding is spot-on. I would suggest you run 10mm2 live and neutral conductors with a 6mm2 earth between the 2 DBs.

Thanks Superdiy

Now I just need to start the actual install and decide on the batts

Link to comment
Share on other sites

Hi Thys

 

Notice you have a fuse and a battery disconnect/breaker on you cable between the battery bank and the inverter. Have a look at one of these it functions as both.

http://solar.rubiconsa.com/item/switch_fuse_battery_disconnect_2pole_size_00

 

You have to take pics as you go along.

 

Chris

Thanks Chris

 

I will look at something similar in Pretoria.

Do you maybe know the price on them?

Yes I will definitely take pictures  :)

Link to comment
Share on other sites

Just a small problem with your drawing.

You have no E/L protection for your plugs fed from the invertor, and this is not legal.

You would need to install an E/L unit just after your change-over switch.

Is that not an EL just below the inverter in the drawing?

Link to comment
Share on other sites

Well, if it was me, I would rather install the E/L in the same DB next to the breakers it is feeding.

If the DB and inverter is some distance from each other, it could make things very difficult if things start tripping.

Link to comment
Share on other sites

Well, if it was me, I would rather install the E/L in the same DB next to the breakers it is feeding.

If the DB and inverter is some distance from each other, it could make things very difficult if things start tripping.

That DB is full would have loved that too.

I'll just hope I don't get any visits from Murphy

Link to comment
Share on other sites

The inverter input and output have separate earth wires to the same earthbar, the inverter earth terminals must be common.

Not a problem, just trying to save you money  :D

 

I also prefer to have the isolator before the fuse protecting the battery or any other equipment.

Link to comment
Share on other sites

Hi all

 

First time post.

 

@Viper_za: Have you already connected everything up?

 

@Eugene: I saw the same thing looking at the diagram. The inverter input earth and output earth go to the same earthing bar. At the same time the inverter neutral output goes to the same earth bar. I am not sure but it looks like the inverter neutral is bonded to earths, the inverter earth and the earth coming from mains. I believe this is going to pose a problem.

Link to comment
Share on other sites

Hi all

 

First time post.

 

@Viper_za: Have you already connected everything up?

 

@Eugene: I saw the same thing looking at the diagram. The inverter input earth and output earth go to the same earthing bar. At the same time the inverter neutral output goes to the same earth bar. I am not sure but it looks like the inverter neutral is bonded to earths, the inverter earth and the earth coming from mains. I believe this is going to pose a problem.

Hi Warren

 

No I have not connected anything yet.

Yes eventually all earths go to the same point. All so close to the inverter I can run seperate cables for each earth :)

For the neutral bonding this is something that is having a big debate on the Mybroadband forum (not sure if i'm allowed to post the link here)

The reason for this bond is so that when the battery or PV supplies the power you have no earth bond for your E/L to work.

But when Eskom supplies we have a problem with two bonds.

One suggested solution that might work is the following from the other forum

 

"A DC relay could be powered from the internal bypass relay to be sure that you disconnect the earth-neutral bond if it ever goes into bypass mode. Otherwise a microcontroller could read the state and control the relay without having to modify the inverter."

 

Any ideas on this here?

Link to comment
Share on other sites

I don't see any problem if you bond all Earths together as well as the Neutral and Earth on the inverter output and have another ELR on the inverter output, BUT then the inverter/UPS mains input connection must be connected before the existing ELR.

 

If you connect the inverter mains connection after the existing ELR and you bond the Neutral and Earth on the inverter output and the inverter is not running (mains goes straight through to output) or if the Neutral input and Neutral output of the inverter is always connected inside the inverter, the main ELR will trip.

 

Please post the link to the MBB thread.

Link to comment
Share on other sites

I don't see any problem if you bond all Earths together as well as the Neutral and Earth on the inverter output and have another ELR on the inverter output, BUT then the inverter/UPS mains input connection must be connected before the existing ELR.

 

If you connect the inverter mains connection after the existing ELR and you bond the Neutral and Earth on the inverter output and the inverter is not running (mains goes straight through to output) or if the Neutral input and Neutral output of the inverter is always connected inside the inverter, the main ELR will trip.

 

Please post the link to the MBB thread.

Hi Superdiy

 

It starts on post count 614

http://mybroadband.co.za/vb/showthread.php/700558-Axpert-invertors/page41

Link to comment
Share on other sites

lol. I know. I have been following the post as I am waiting for an answer from the supplier's installer who I bought my kit from. My installation is about 80% complete and then I ran into the bonding issue. It has become so confusing as everybody kind of has a point in one way or the other. The issue I see is not everybody's inverters are the same make. Some are internally bonded where others are not.

 

My conundrum is I would like to see a system like this installed and working before I do any power up of any sort. I was thniking  of connecting some of it up and then doing some testing with my multimeter. My concern is I dont want to blow my inverter or have a family member get a shock. I tried to post my installation on your forum but for some reason it timed out and did not work. I will try again. viper I see you in Pretoria. I am in Centurion (Midstream Estate).

 

I have set it up to wire before the main panels EL as it will trip like you say. I will be installing another EL in the inverter DB panel for the plugs which will be dedicated to the inverter only. These plugs will be installed off grid permanently as in the picture below except the one is dedicated and the other is eskom. I have already bought one. I will post a picture of that one too

 

CBi-Metal-Double-Dedicated-Switched-Sock

Link to comment
Share on other sites

Okay I finally got my showcase posted but my images are linked to dropbox as the images are in a format this site does not like.

 

http://powerforum.co.za/topic/262-my-system-installation-diy-almost-complete/#entry2009

 

I will also keep in touch as to when the supplier's installer has given me feedback. I will post my wiring diagram on the topic link above.

Link to comment
Share on other sites

 

I've commented on that thread and I'm still waiting for a clear solution. A few people have made valid comments and a SANS UPS connection diagram was also posted, but in my opinion that diagram is incorrect since it will not give you any E/L protection on the inverter circuits when the inverter supplies the load.

 

I can't believe that there is no clear answer to this (yet) - obviously inverters and UPS's were not installed in August 2015 for the first time - or were the installations never done safely and correctly in the past?

Link to comment
Share on other sites

  • 2 weeks later...

I've commented on that thread and I'm still waiting for a clear solution. A few people have made valid comments and a SANS UPS connection diagram was also posted, but in my opinion that diagram is incorrect since it will not give you any E/L protection on the inverter circuits when the inverter supplies the load.

 

I can't believe that there is no clear answer to this (yet) - obviously inverters and UPS's were not installed in August 2015 for the first time - or were the installations never done safely and correctly in the past?

 

I contacted an installer from the company that I purchased my kit from. To Quote him

"The inverter must be bonded in a seperate box between the inverter and Inverter DB panel as per compliance for COC."

He did not mention anything about a relay and I cannot get a reply from him. Will update again when I find out more. :)

Link to comment
Share on other sites

I contacted an installer from the company that I purchased my kit from. To Quote him

"The inverter must be bonded in a seperate box between the inverter and Inverter DB panel as per compliance for COC."

He did not mention anything about a relay and I cannot get a reply from him. Will update again when I find out more. :)

 

It is totally dependent on the type of installation. Stand alone / off grid installations and installations where the whole house is connected to the inverter and the inverter AC input is left unconnected are not a problem. Installations where a part of the installation is powered by the inverter and the inverter is used as a UPS is still a problem. If you are referring to the second type of installation your installer probably do not want to go into detail because he also does the connection it in a certain way which either satisfies SANS or the E/L test when issuing a CoC. Currently we were unable to get a solution which satisfied both SANS and the E/L test required for a CoC in this type of installation. There are 2 possible solutions however, but it is not clear if any one of the two would satisfy the SANS regulation.

Link to comment
Share on other sites

I can't believe that there is no clear answer to this (yet) - obviously inverters and UPS's were not installed in August 2015 for the first time - or were the installations never done safely and correctly in the past?

 

I think you are touching on a vary valid subject matter.

Link to comment
Share on other sites

Hi jdp, the earth connections is extremely important to ensure correct operation of earth leakage units and circuit breakers under earth fault conditions.

 

If your protection circuits are not operational then your system is a risk to human safety and also a fire hazard.

 

Please don't run your system if your earthing and protection circuits are not operational.

 

Follow Superdiy's temporary solution and then test that the protection circuits are working. Also place a sign at your main DB board to not isolate that switch while the inverter is operating. This is to ensure that your neutral / earth connection remains intact.

 

If you make use of the supplied neutral earth connection then you have to consider that this could result in a long earth fault current return path and will therefore lower the prospective earth fault current. So you would have to check either via calculation or measurement that the resistance of this path is in compliance with SANS 10142.

 

I have requested advice and a permanent solution from Mustek.

Link to comment
Share on other sites

I've also wondered about these requirements. Thing is, if you bond Neutral to Earth a second time downstream from an existing EL, then you just created a second path to ground, and whenever you do that, the upstream EL will always trip. So you cannot have an EL both before and after the inverter. Also, your inverter must not be one of these cheapies with the floating ground, because if you ground the neutral on these it shorts out one bank of power transistors and the magic smoke comes out.

 

Anyway, so I have an interesting setup with my Victron Multiplus. Because they make these things to work on boats, and because a boat should not be grounded to land (because it causes galvanic corrosion to the hull), it has a grounding relay that works with the transfer switch. When running from grid power, ground is connected to "shore ground", and when running from the inverter, it is connected to the inverter case (which is grounded to the boat's hull).

 

Now what I did is ground my inverter's case to the earth bar in my DB board. So when running from inverter, it ties Neutral to ground (so the required "bonding" is in place), and when it is running from the grid, the bonding is removed and it becomes a pass-thru (but it is bonded upstream, so bonding is still in place). This means I can have an EL before and after the inverter without problems.

 

Now I wonder if this setup can be approved :-)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...