Axpert invertors

Axpert MKS 5kVA inverter installation

Hi,

Continued from my previous post...

Also make sure to add additional safety on the high current DC lines. I added this 125A fuse inline as a last-resort fail-safe. This fuse is not cheap (it costs R72 at RS components), but is has a high rupture capacity and is guaranteed not to explode in your face:

125A-fuse.jpg

After crimping and heat-shrinking both ends (can never have too much safety insulation), the connections are screwed into the bottom of the inverter. Make sure you screw these in first and then wire up the battery terminals. The reason for this is that the initial inrush-current to the inverter can cause a spark when you complete the DC circuit:

Inverter-connection.jpg

Make sure your battery terminals are covered/protected. The amount of energy in those batteries is immense - you don't want to accidentally drop a screwdriver or other bit of metal (think rings, jewelery, watches, etc) on those terminals and loose a hand or worse. The 170Ah lead-crystal batteries that I got come with their own terminal covers and terminal bridges. Makes installation quick and easy:

170Ah-batteries.jpg

Make sure you understand the cabling and charging requirements of your batteries so that they match the settings on the inverter. The default settings are okay-ish for normal GEL or lead-zink acid batteries.

The completed inverter installation:

final-install.jpg

Finally, the moment of truth. With the batteries connected, turn on the inverter at the switch located (hidden) at the bottom-right of the inverter. It should fire up within a few seconds and complete a self-test. Here's mine showing my house's evening base-load (lights, TV, computers, other misc electronic stuff):

Axpert-LCD-display.jpg

A word on test gear. It is essential, no, make that mandatory, to have tools that can measure voltages and detect NFV (near-field voltages). A NFV detector costs about R170 at Communica, but it can save your life by detecting dangerous voltages on equipment that you are working on. Always, always, sweep your NFV detector over any DB or wiring that your are working on. Make sure you switch off all breakers, including the mains trip switch and the external breaker to your house.

Also be very aware of the fact that the inverter can produce lethal voltages on its own, without the mains breaker being on.

Shown below is a good quality multimeter and an NFV detector:

test-gear.jpg

Some final thoughts:

I asked a qualified electrician to vet my installation in order for it to be certified. He had the following comments:

1. The isolator to the inverter must rather be a breaker on just the Live feed wire. The reason is that Neutral feed must not be interrupted, else the earth-leakage switch after the inverter will not trip when a ground-fault is present. This is for me to fix.

2. He said that he'd prefer a Neutral busbar in the second DB, but seeing that theer are no feeder switches, he was happy to let this pass.

3. I need to add an indicator warning light to show when the inverter output is live. This is to warn any 3rd-party that a dangerous potential exists, even though the mains feed is switched off. For me to fix.

4. The mains trip-switch and the inverter trip-switch should be linked together (i.e. if either trips, the other should trip as well). However, he did a ground-fault test and both trip switches did trip. He was happy to COC like this, but did note that a situation can exist where the inverter and mains switched both trip, but only the inverter switch is then turned on after a while. In this case the Neutral feed back to the street is interrupted and GFP is no longer valid.

I'd appreciate any feedback and suggestions from other forumites (esp savage!).

--deckert
 
Hi deckert,

That is a thorough writeup.

I have been thinking about the GFP problem and I do not have an answer yet, so maybe we can get some input on that. I have been looking at savage's post and drawing in the "How to wire an inverter into my DB board" thread and also the SANS 10142-1:2012 document, specifically pages 355-358 where they have drawings of various generator and UPS setups wired into the DB.

The SANS drawing with a generator, have earth and neutral connected at the generator, but the UPS setup, figure S.3 on page 357, does not have that. So in that figure, if the Mains CB or Earth Leakage (both of which cuts both live and neutral in the figure) open, the earth leakage behind the UPS / Inverter might not work properly anymore.

I was ready to have double pole breaker between the grid and my inverter because that can serve as an isolator when woring on the inverter, but I guess I need to rethink that a bit.

BTW how does people do the indicator lamp in the DB? My DB is an old Fuchs rail, slowly getting populated with mini rail adapter plates, but I have not seen indicator lamps for mini rails. Or does one just build your own?

John
 
JohnHay said:
Hi deckert,
...
The SANS drawing with a generator, have earth and neutral connected at the generator, but the UPS setup, figure S.3 on page 357, does not have that. So in that figure, if the Mains CB or Earth Leakage (both of which cuts both live and neutral in the figure) open, the earth leakage behind the UPS / Inverter might not work properly anymore.
...
John
Click to expand...

I can confirm that I use to have an EL that fed the inverter and the geyser. Behind the the inverter output I had another EL that fed the individual CBs. When you performed the EL tests only the main EL would trip and not the one behind the inverter output. Had to remove the EL before the inverter. Everything but the inverter is now on the one EL. Not sure how to solve the issue with the inverter itself not being on the EL though since that causes the EL, behind the inverter output, to stop functioning.
 
oober said:
I can confirm that I use to have an EL that fed the inverter and the geyser. Behind the the inverter output I had another EL that fed the individual CBs. When you performed the EL tests only the main EL would trip and not the one behind the inverter output. Had to remove the EL before the inverter. Everything but the inverter is now on the one EL. Not sure how to solve the issue with the inverter itself not being on the EL though since that causes the EL, behind the inverter output, to stop functioning.
Click to expand...

But even if you wire your inverter to not go through your main E/L as in savage's drawing, if your main switch is a double pole, as most drawings have it, your inverter can be up and running, but the E/L behind it will not work anymore because the Earth and Neutral connection is broken?

John
 
JohnHay said:
But even if you wire your inverter to not go through your main E/L as in savage's drawing, if your main switch is a double pole, as most drawings have it, your inverter can be up and running, but the E/L behind it will not work anymore because the Earth and Neutral connection is broken?

John
Click to expand...

You mean to say if you have a double pole main switch and it is OPEN and then you test the EL it won't trip? I don't think I have tested it in that scenario yet.

Edit. And my electrician which gave me a COC replaced my old single pole breaker(main switch) with a double pole breaker...geez I don't think he knew what he was doing then.
 
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Not sure if this helps... but in bypass mode, the internal relay connects the input and output Live, Neutral and Earth. So in that mode, the E/L should work, as your DB will have the Neutral tied to Earth. But in "battery" mode, the neutral is floating. So the E/L won't work.

This is referring to the E/L on the output of the inverter.

Not sure if that makes sense...
 
JohnHay said:
Yes that is what I meant, although not exactly what I have written. :)
Click to expand...

I need to get one of those EL testers and check what happens. Although it is unlikely that I will have my main(dbl pole) open and the inverter running, but it's a possibility.
 
greg_SA said:
Not sure if this helps... but in bypass mode, the internal relay connects the input and output Live, Neutral and Earth. So in that mode, the E/L should work, as your DB will have the Neutral tied to Earth. But in "battery" mode, the neutral is floating. So the E/L won't work.

This is referring to the E/L on the output of the inverter.

Not sure if that makes sense...
Click to expand...

Yeap makes sense. One could also argue since the neutral is floating that it is not as dangerous, since you can't complete the circuit to ground. But in some instances inverters are ground internally so what happens then?

Edit. Must say I find it a bit confusing. :D
 
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Hmm - interesting, and haven't thought about that one yes...

The obvious thing then would be to isolate (separate) the earths too... So all the earths behind the inverter would go directly to the ground/earth post, and neutral / earth behind the inverter would need to be connect to each other (before the EL).
 
If it is just a plain DB -> AC inverter, I agree. That is in effect like a generator and there SANS show that you tie the earth to the neutral at the generator. But what about these fancy ones like the Axpert and Infinisolar that also have a mains feed and earth terminals on both the input and load side? Will a separate earth on its output not cause problems in the "normal" case where all is working and you have lightning? Because you then have earth connected to the inverter from different sources? Or do propose to bring the earths together again somewhere? BTW I measured my Infinisolar and its to earths (input and load) are tied together inside.

John
 
JohnHay said:
Will a separate earth on its output not cause problems in the "normal" case where all is working and you have lightning?
Click to expand...

It may cause issues for things that sit behind the earth leakage, but definitely not for things before / in front of the earth leakage (lights / dedicated plugs, etc). Honestly, I need to talk to some people (master electricians) about this, more than likely on Friday evening.

JohnHay said:
BTW I measured my Infinisolar and its to earths (input and load) are tied together inside.
Click to expand...

I actually suspected that. Again, depending on how / where the Inverter is installed, that may not necessarily be a bad thing.
 
savage said:
It may cause issues for things that sit behind the earth leakage, but definitely not for things before / in front of the earth leakage (lights / dedicated plugs, etc). Honestly, I need to talk to some people (master electricians) about this, more than likely on Friday evening.



I actually suspected that. Again, depending on how / where the Inverter is installed, that may not necessarily be a bad thing.
Click to expand...

Awaiting some feedback regarding the EL and double pole breakers from those masters. :D
 
greg_SA said:
Was this in Bypass mode or battery mode?
Click to expand...

That was in off mode, ie. no power anywhere. :) I'll see if I can check other modes, but suspect that the inverter does not switch the earths. I cannot check battery mode yet because my batteries are still in China... If lsheed is still going ahead with the group buy. :)
 
Just BTW...

Got my first eskom bill since my setup went live... I came down from an average bill of R3500, to my bill now of R760 :D

Granted, I have PV installed (3kWp), and changed basically every single light on my property to LED.

I'm over the moon, to say the least!!!

EDIT: Lowest bill I have ever received since I've bought this house some 5 years ago...
 
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savage said:
Just BTW...

Got my first eskom bill since my setup went live... I came down from an average bill of R3500, to my bill now of R760 :D

Granted, I have PV installed (3kWp), and changed basically every single light on my property to LED.

I'm over the moon, to say the least!!!

EDIT: Lowest bill I have ever received since I've bought this house some 5 years ago...
Click to expand...

Congrats :) Would be interesting to know how much the non-solar changes actually made. A R3500 bill is insane! Are you running a smelter at home? :D
 
Noob question alert.

Hiya...

These Axpert inverters seem VERY popular here on mybb.

I've been reading these threads (Inverters, batteries, ups, PV etc.) for a few months now to familiarise myself a bit on the topic. Still very out of my depth though. Especially when it comes down to the usage calculations etc.

I also just learnt from some of these threads that my current genny setup (male-to-male) plug is a really idea - Despite the fact that it seems to be the way that most ignorant people like me are doing it. (I'm having an electrician come around tomorrow to quote me on the correct setup and don't plan on using the genny again until its properly hooked up.)

Quick question on the Axpert Inverter. When I'm load shed I run a gas powered genny which handles my load perfectly.
Rated Output Power (kW) 4.2
Maximum Output Power (kW) 4.5
(I make sure that the Mains, geysers, pool pumps etc are all off when running the genny.)

Taking the above output into account am I correct in assuming then that I'd be ok to look more into an Axpert 5kva (4k watt) to handle my load? Bearing in mind that I already cook on gas and I'm also converting to gas geysers in the near future.

Obviously i'd still need to check my exact usage needs and calculate number of batteries etc but I want to know for now if the Axpert 5kva would suit my current needs. Also I do plan to expand at a later stage to add PV's to reduce my reliance on Eskom as much as possible.

For now though I'm looking to get something to get me through a few hours of load shedding with a generator as backup to the battery backup if that makes sense.
 
Deckert said:
Hi,

Continued from my previous post...



The completed inverter installation:

View attachment 225360

Finally, the moment of truth. With the batteries connected, turn on the inverter at the switch located (hidden) at the bottom-right of the inverter. It should fire up within a few seconds and complete a self-test. Here's mine showing my house's evening base-load (lights, TV, computers, other misc electronic stuff):

View attachment 225358


--deckert
Click to expand...

Very naas :)
 
Easy way to test if your earth leakage will work is to use a multimeter between live and earth , if you get mains voltage it should trip
 
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