Inverter AC isolator

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JamieP
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Inverter AC isolator

Post by JamieP »

Now, I've always installed these and was always under the impression I had to but actually looking now I'm not 100% sure if it's actually required for compliance

Looking at the 2016 version of 4777.1, it's most definitely needed unless the inverter is adjacent to the switchboard it's connected to (clause 3.4.3) so within 1.25m of the switchboard (using 3000:2018 definition of adjacent)

But looking at the cited 2005 version of 4777.1 I can only see it asking for an isolation device and that it shall be installed to the requirements of main switches (clause 5.3.3)

I did also see 7.3.4.1 in 3000 but at the bottom it has an exception which made me believe if you just complied with 4777 none of that applied and as above, 4777.1 2005 only calls for a device at the switchboard

Obviously it would be wise to adhere to any of the additional requirements of 4777.1 2016 regardless of citation and I'll probably keep installing isolators unless the inverter in adjacent to the switchboard but I was just wondering about the technical side of it
AlecK
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Re: Inverter AC isolator

Post by AlecK »

Look at "3000" 2.3.3.1.
Every supply to an installation requires a "main switch" at MSB.
Exception allows "main switch" for an alternative supply to be at a different switchboard .

So even though the Exception to 7.4.3.1 means you don't have to follow details (a) to (e) as long as you follow 4777.1; it doesn't switch off 2.3.3.1
Which us exactly what cited edition of 4777.1 says: the inverter output needs an isolator, and that isolator has to comply as a "main switch".
JamieP
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Re: Inverter AC isolator

Post by JamieP »

Yes I agree

More what I was asking is under current rules is there also a requirement for an additional isolator adjacent to the inverter as well as the solar mcb/isolator
AlecK
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Re: Inverter AC isolator

Post by AlecK »

Whether an output isolator is required is 7.3.4.
So the default is that an output isolator is required adjacent to, or on, the generation system.
That means unless the generating system is adjacent to the switchboard, you need 2 switches: one adjacent and one at swbd

For an engine-driven genset, "3010" requires an output isolator in every case.
But "4777.1" doesn't; so the effect of the Exception to 7.3.4 is that for an grid-connected inverter system you only need the swbd "main switch".

Not a lot different from the network mains; the user of the installation can't isolate those either
JamieP
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Re: Inverter AC isolator

Post by JamieP »

This is what I was thinking, very interesting because I've always been taught that it was needed

4777.1 2016 does call for an additional one near inverter unless the inverter is adjacent to the switchboard it's connecting too so I wonder if it's a case of people reading this instead
AlecK
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Re: Inverter AC isolator

Post by AlecK »

Could be; and that would align with '3010".

And when the citations in Schedule 2 change; we'll have a lot of changes , across a lot of standards, all coming into force at once.
Instead of they way Oz does it; with each State adopting revisions as they come - typically with a 6-month from publication date before coming into force
JamieP
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Re: Inverter AC isolator

Post by JamieP »

Yeah it's such a pain really, so many standards have new versions now but we are stuck working on the old ones, oh well, just the way it is isn't it. I think more the issue is people not even knowing how to know which ones to use

Any how thanks for the input as always Alec, much appreciated
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