Jump to content
Thank you for the great forum, Safe Driving over the weekend. Sincerely Jason
Energy

Complies with local NRS 097-2-1 regulations?

Recommended Posts

Hi Guys, Hoping you can help.

I would like to know. A grid tie inverter that is not certified and does not carry the 

  • Complies with local NRS 097-2-1 regulations

 May a unit be legally installed if the Sell back function is turned off on the inverter?

The unit does comply to many other foreign certifications. EU , AU and further.

Thanks Guys

Jay

Share this post


Link to post
Share on other sites

The last conversation I had with the City of Cape Town which was 2 months ago, I was told that any inverter that is connected to the grid, even if it does not feed back in to the grid must be NRS certified and the installation must be registered.  I'm not sure about other areas in S.A

Share this post


Link to post
Share on other sites

nope it is not then legal. it has to carry a certificate and / or test result stating it conforms to NRS097-2-1 and ammendments

Share this post


Link to post
Share on other sites
On 1/9/2017 at 4:43 PM, Mike said:

nope it is not then legal. it has to carry a certificate and / or test result stating it conforms to NRS097-2-1 and ammendments

Mike, will TCOC not accept the installation if an after market grid tie limiter is installed in between? I don't know their rules, but I'm curios to know whether those stand alone units, which do comply, will help with getting the whole system to comply if the inverter doesn't?

Share this post


Link to post
Share on other sites
2 hours ago, SilverNodashi said:

stand along units, which do comply

It actually has nothing to do with grid-limiting, it has to do with anti-islanding. There are two things the city don't want you to do, the first is spinning the meter backwards, the second is accidentally creating a powered island. NRS-097-2-1 is about the second half of that problem.

The Victron documentation specifically states that a Multiplus combined with a Ziehl UFR-1001e does comply with NS-097-2-1. The Ziehl itself is on the CoCT list. It's possible that adding this device to other inverters will also be sufficient, but I think this has to be tested on a case-by-case basis and you cannot just assume that this is sufficient. I'll attempt to explain my own understanding thereof, which may or may not be accurate.

NRS-097-2-1 says you must have two switches, one of which must be physical (not electronic). In the case of the Multiplus, it already has one electronic switch which is sufficient in some markets (eg the UK), so when you install a Ziehl in front of a Multiplus, you only use the one contact to drive a contactor, though the Ziehl itself can handle two. In other words, the anti-islanding isn't down to just the Ziehl device, in this case it is the combination of the two that is compliant.

Second, purely passive anti-islanding will always have a non-detection zone. As far as I know, if you want any sort of certification, there has to be a measure of active detection in your inverter. Active measures usually means the inverter deliberately leans to the left just a tiny bit so that when the grid goes out it falls off the horse very quickly.

As I said though, the Ziehl is on the list on its own. I'm not sure what that means :-)

Share this post


Link to post
Share on other sites

Top right it has two contacts, so it has the ability to operate both the switches required for anti-islanding. It is however purely a passive device, so it needs the inverter itself to implement certain active measures.

When used with something like the Multiplus, you only use the contact on the left (K1).

14642510_10154460186120619_2249146367059899180_n.jpg

Share this post


Link to post
Share on other sites
4 hours ago, plonkster said:

It actually has nothing to do with grid-limiting, it has to do with anti-islanding. There are two things the city don't want you to do, the first is spinning the meter backwards, the second is accidentally creating a powered island. NRS-097-2-1 is about the second half of that problem.

The Victron documentation specifically states that a Multiplus combined with a Ziehl UFR-1001e does comply with NS-097-2-1. The Ziehl itself is on the CoCT list. It's possible that adding this device to other inverters will also be sufficient, but I think this has to be tested on a case-by-case basis and you cannot just assume that this is sufficient. I'll attempt to explain my own understanding thereof, which may or may not be accurate.

NRS-097-2-1 says you must have two switches, one of which must be physical (not electronic). In the case of the Multiplus, it already has one electronic switch which is sufficient in some markets (eg the UK), so when you install a Ziehl in front of a Multiplus, you only use the one contact to drive a contactor, though the Ziehl itself can handle two. In other words, the anti-islanding isn't down to just the Ziehl device, in this case it is the combination of the two that is compliant.

Second, purely passive anti-islanding will always have a non-detection zone. As far as I know, if you want any sort of certification, there has to be a measure of active detection in your inverter. Active measures usually means the inverter deliberately leans to the left just a tiny bit so that when the grid goes out it falls off the horse very quickly.

As I said though, the Ziehl is on the list on its own. I'm not sure what that means :-)

Thanks for this great explanation. The inverter that I have my hopes on makes use of the " Eastron modbus meter, positioned in-between the Eskom meter and Inverter to act us a grid tie limiter. I feel the Eastron could be on the legal list :> But the inverter only holds foreign certifications. Wonder if the addition of the Eastron changes matters?

Sincerely

Jason

Share this post


Link to post
Share on other sites
Just now, Energy said:

Wonder if the addition of the Eastron changes matters?

That's just a power meter, which is going to do nothing at all for anti-islanding :-)

I have no idea what it takes to get an inverter tested by CoCT. If it is as simple as supplying them with one (and hopefully not paying for it yourself), that might be the way to go.

I'm hoping that the Victron Multigrid (which has VDE AR 4105 certification already) will be added to the list this year. I'll see if I can find out for you when I talk to the big irons again :-)

Share this post


Link to post
Share on other sites
6 minutes ago, plonkster said:

That's just a power meter, which is going to do nothing at all for anti-islanding :-)

I have no idea what it takes to get an inverter tested by CoCT. If it is as simple as supplying them with one (and hopefully not paying for it yourself), that might be the way to go.

I'm hoping that the Victron Multigrid (which has VDE AR 4105 certification already) will be added to the list this year. I'll see if I can find out for you when I talk to the big irons again :-)

CoCT do not test the inverters they need to be sent to a testing facility like TUV Rheinland or Bureau Veritas to be certified for NRS which cost quite a bit of money if you are a local manufacturer.  I know MLT Inverters had a professor from Stellenbosch university do the testing on their inverters for the NRS, but they had to go through a lot of red tape before it was allowed.  

Share this post


Link to post
Share on other sites

On the topic of Anti-islanding gadgets.

An alternative anti islanding unit which could give you compliance to NRS would be a UFE ENS26-A

According to their website (and only when navigated in German) states that NRS 097-2-1:2010 exists as a "country setting".

They don't seem to have a certificate available to confirm compliance on their site, but they might provide it if you enquire.

Wiring of the ENS is simpler than the Ziehl unit, as all the switching is contained inside the unit. You connect an incoming Live and Neutral, and a outgoing pair. That's it.

The unit lacks the meat of the Ziehl, and can only handle 5kw of grid feed on its internal contacts.

I stand to be corrected, but I think the ENS system is used in some Steca GTI's to give them anti-islanding capabilities.

Plonkster - on the Zeihl, can you program a connection delay onto the relay? I.e. The unit will only reconnect to the grid if it's been healthy for, say, 20 min?


Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

Very Interesting. Thanks all. Find attached Certification list of the units I would like to test and bring to the store. I am wondering if any of these certs supersede our NRS.

The Top Two VDE Certs seam to carry some weight from what all the guys me. As attached. What do you all think?

Sincerely

Jay

Certs.JPG

Share this post


Link to post
Share on other sites
47 minutes ago, NickNou said:

An alternative anti islanding unit which could give you compliance to NRS would be a UFE ENS26-A

As I recall it is slightly cheaper too. They quoted me 340 Euro back in August 2014. Of course our exchange rate got hurt somewhat since then, but I suspect the euro price will stay more or less the same. In contrast the Ziehl is around 450 Euro.

 

47 minutes ago, NickNou said:

can you program a connection delay onto the relay?

I don't know. It has a delay as per the program you select, which depends on the specification for that country. I don't think any of the programs do as much as 20 minutes, but 20 seconds is doable. That's in the spec as far as I know: That before a GTI may connect it has to look for a stable voltage for some seconds (depending on the program again).

You can always check the english manual. Google finds it quick quick. It only ships with a German manual. Reading that was a lot of fun. My German only extends to basic stuff and ordering food in restaurants :-)

So from a quick scan, it seems that you can set the doF delay, look around page 16. As high as 999 seconds, which isn't quite 20 minutes, but close :-)

Share this post


Link to post
Share on other sites

I was just thinking in terms of letting the grid stabilise before you reconnect.

Let's assume a storm passes through your area and causes the grid to dip, surge or go out sporadically. You would want to keep your inverters islanded until you know the grid is stable and won't damage anything.

Going off your mail above, 999 seconds would be in the right ball park I guess.

Nevertheless - l don't want to deviate too much form the NRS discussion.


Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites
12 hours ago, plonkster said:

It actually has nothing to do with grid-limiting, it has to do with anti-islanding. There are two things the city don't want you to do, the first is spinning the meter backwards, the second is accidentally creating a powered island. NRS-097-2-1 is about the second half of that problem.

The Victron documentation specifically states that a Multiplus combined with a Ziehl UFR-1001e does comply with NS-097-2-1. The Ziehl itself is on the CoCT list. It's possible that adding this device to other inverters will also be sufficient, but I think this has to be tested on a case-by-case basis and you cannot just assume that this is sufficient. I'll attempt to explain my own understanding thereof, which may or may not be accurate.

NRS-097-2-1 says you must have two switches, one of which must be physical (not electronic). In the case of the Multiplus, it already has one electronic switch which is sufficient in some markets (eg the UK), so when you install a Ziehl in front of a Multiplus, you only use the one contact to drive a contactor, though the Ziehl itself can handle two. In other words, the anti-islanding isn't down to just the Ziehl device, in this case it is the combination of the two that is compliant.

Second, purely passive anti-islanding will always have a non-detection zone. As far as I know, if you want any sort of certification, there has to be a measure of active detection in your inverter. Active measures usually means the inverter deliberately leans to the left just a tiny bit so that when the grid goes out it falls off the horse very quickly.

As I said though, the Ziehl is on the list on its own. I'm not sure what that means :-)

Oops, sorry for the typo ;)

 

I get what you're saying and it makes a lot of sense - the inverter has to know about the grid all the time, it's not just about the grid tie limiter. 

BUT, what if one doesn't want to feed back to the grid, would they accept that, that a grid tie limiter is good enough for their safety? 

Share this post


Link to post
Share on other sites
1 hour ago, NickNou said:

Let's assume a storm passes through your area and causes the grid to dip, surge or go out sporadically. You would want to keep your inverters islanded until you know the grid is stable and won't damage anything.

These anti-islanding devices will disconnect very quickly if the voltage or frequency goes out of range. After that it will remain disconnected until the voltage and frequency is back in range (apparently it ignores Vector shift during this time and monitors just the rest), and once it is stable it will count down between 20 and 60 seconds (depending on program) and then reconnect.

I've watched the Ziehl on a non-stable waveform. It will start at 20 seconds (on the UK program I think), it will sometimes remain on 20 seconds for a while (waiting for the things to stabilise) and then it will start counting down. If one of the parameters shift, it goes back to 20 and starts over. It only switches on once everything is stable plus another 20 (or whatever you configure) seconds.

So I doubt you have to set this to any more than a minute.

Share this post


Link to post
Share on other sites
11 minutes ago, SilverNodashi said:

grid tie limiter is good enough for their safety?

Grid limiters are never exact, they sort of hover around zero, they are never exactly zero unless you have a very accurate meter and a very stable load. If you feed back as little as a few watts (20mA or so) it is enough so shock a line worker and potentially kill him.

We've had this discussion before on another thread, the sort of conditions that you need for such a thing to happen could only be described as a corner case. In 99% of cases the grid goes out and turns into a low impedance shunt that immediately changes the impedance that your inverter is pushing into: an islanding event so large that if you miss it the inverter will just die due to overload. It's the 1% case that rightly has some people asking whether anti-islanding is even worth all the effort that is being spent on it.

Whatever your take on it... the fact is that that is what the regulation says.

Share this post


Link to post
Share on other sites
10 hours ago, SilverNodashi said:

Oops, sorry for the typo ;)

 

I get what you're saying and it makes a lot of sense - the inverter has to know about the grid all the time, it's not just about the grid tie limiter. 

BUT, what if one doesn't want to feed back to the grid, would they accept that, that a grid tie limiter is good enough for their safety? 

As far as I know even if you do not want to feed power back to the grid using a grid limiter, if the inverter does not have a NRS certificate they do not accept it.  When you install a system you have to register the system with the CoCT, same with Stellenbosch Municipality and Drakenstein Municiplality.  If you do not want to feed into the grid then you register the system for self consumption.  You have to fill in the application form and with that you need to send the electrical CoC and PR. Eng certificate/letter for the installation as well as a line diagram of the installation and the certificate for the inverter where it states that it is NRS compliant. 

So even if you put a grid limiter on an inverter and the inverter certificate has all the European and whatelse compliant standards on it, if it does not show NRS they don't see it as being save.  You can take a chance and install the system but if they notice your system is not registered they send a letter stating that you need to register the system and if you don't do it within a month, they will disconnect you from the grid.

Share this post


Link to post
Share on other sites

I mentioned earlier that I would ask about certification, not that it is of interest to all people here ( :-P ) but the Victron Multigrid has now passed both the German and Australian certifications, and South Africa is next on the list. So by the 3rd quarter we will hopefully have a blue inverter on the CoCT list :-)

Share this post


Link to post
Share on other sites
1 hour ago, plonkster said:

I mentioned earlier that I would ask about certification, not that it is of interest to all people here ( :-P ) but the Victron Multigrid has now passed both the German and Australian certifications, and South Africa is next on the list. So by the 3rd quarter we will hopefully have a blue inverter on the CoCT list :-)

Only certain models, or all of them?

Share this post


Link to post
Share on other sites
Guest

@plonkster will the new Multigrid keep on operating if the grid is off and you have batteries connected to it?

Or will it like the grid tie inverters stop?

Share this post


Link to post
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.


Topics

Contact Us - Power Forum South Africa

×
×
  • Create New...