Pv on rcd

[davesparks]

Don't see why an RCD would be affected by the inverter being referenced to earth?
Difficult, I'd say virtually impossible with a TT installation.

In a TT you would still want to design the circuit to not need 30mA RCD, only the fault protection RCD which is likely to required, and ensure that the inverter used does not include a N-E link so providing a n electrically separate supply when not connected to the grid.


In theory (and yes it is an unconomical and borederline daft theory) you could avoid any RCD protection completely by using double insulation as the protective measure for the circuit instead of ADS, or even electrical separation. Or of course by getting the Ra low enough to not require RCD

 

[Leesparkykent]

Just in city's at the mo and flicking through the PE magazine and napit have just written an article on this and says the rcd must be located at the inverter end. Page 37 of Febs PE magazine if any ones interested.

 

[gnselectricals]

Just in city's at the mo and flicking through the PE magazine and napit have just written an article on this and says the rcd must be located at the inverter end. Page 37 of Febs PE magazine if any ones interested.

Off to the salers now will have a look cheers

 

[Worcester]

Just in city's at the mo and flicking through the PE magazine and napit have just written an article on this and says the rcd must be located at the inverter end. Page 37 of Febs PE magazine if any ones interested.

Now we're going to get even more confused lol

 

[GEOFF S]

But then the grid supply would not be disconnected in the event of a fault.
This is a cable with a source of supply at both ends.

Hi

Im not sure i follow, so lets break things down.

We must not connect to final circuits, so 5 Sec rule applys.

If there is no seperation on the inverter or the PV cable a.c requires rcd prorection then this is placed at the inverter.

Unlike a tx the inverter is not connected to the general mass of earth at the star point.

The PV a.c cable needs to be provided with fault protetcion at the connection to the mains a.c.

If a fault occurs on the a.c system, the power will disconnect within 5 secs, the loss of power will shut the inverter down in milliseconds.

If a fault on the PV cable occurs then the RCD at the inverter operates, thus causing loss of power and inverter shuting down.

If we look at ADS and earting the TX is earthed, so contact with live parts and general mass of earth will give rise to a risk of shock, this isnt the case with the inverter.


Cheers

 

[davesparks]

If a fault on the PV cable occurs then the RCD at the inverter operates, thus causing loss of power and inverter shuting down.

But the faulty cable is also connected to the grid supply, so yes the rcd at the inverter will disconnect the inverter but it will not clear the fault

 

[GEOFF S]

But the faulty cable is also connected to the grid supply, so yes the rcd at the inverter will disconnect the inverter but it will not clear the fault

Hi

But the cable will have protection at the other end as i mentioned, 712.434.1, so with the inverter isolated via the RCD, is it any different to any other circuit not needing rcd protection.

Now if we bury the cable less 50mm, and used standard cable, then yes two rcds at each end would be required, but this can be enginered out using swa etc.

Cheers

Cheers

 

[davesparks]

Hi

But the cable will have protection at the other end as i mentioned, 712.434.1, so with the inverter isolated via the RCD, is it any different to any other circuit not needing rcd protection.

Now if we bury the cable less 50mm, and used standard cable, then yes two rcds at each end would be required, but this can be enginered out using swa etc.

Cheers

Cheers

That was the whole point of the damned discussion, what can be done if the PV cable needs rcd protection!
That is exactly the situation I have been saying you would need two RCDs for.

 

[SibertSolar]

Fascinating...

 

[davesparks]

Fascinating...

It's the first really interesting discussion I've seen on here in ages!

 

[Leesparkykent]

I think the easiest way would be to use a reference method that doesn't require additional protection by means of an RCD ;-)

 

[davesparks]

I think the easiest way would be to use a reference method that doesn't require additional protection by means of an RCD ;-)

Yes, I completely agree, but the discussion has been interesting all the same. It's got me thinking about something properly for the first time in ages.

 

[Leesparkykent]

Yes, I completely agree, but the discussion has been interesting all the same. It's got me thinking about something properly for the first time in ages.

Its defiantly something I want to get to the bottom of as no doubt eventually will end up coming across the situation when surveying/doing a board change.

 

[Energetic]

How about approaching this from the other direction, are there any 3.6kW inverters that are compatible with a 30mA RCD? I think Power One used to do a HF transformered version, at a cost. Was there ever an SMA 3600HF? I once emailed them asking for one...

Seems a big hole in the EU market if there isn't one given the ever increasing requirements for RCD protection.

 

[CBR600]

How about approaching this from the other direction, are there any 3.6kW inverters that are compatible with a 30mA RCD? I think Power One used to do a HF transformered version, at a cost. Was there ever an SMA 3600HF? I once emailed them asking for one...

Ginlong Solis state max 20ma DC injection. We use them on 30ma RCD's without tripping issues.