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a1colly

Hi All,

First time for this so unsure what could be the cause.

CSUN 250 panels - string of 16 connected via 4mm DC cable to Fronius IG TL 4.0 feed to CU via 2.5mm T+E

DC cable run including the array is 22m and the AC run is 12m.

Random tripping of the RCD,

AC circuit is okay continuity and insulation fine, no fault with RCD and Ze on PME is okay. Mains voltage sits at around 245V but have seen some fluctations whilst there which were higher.

DC circuit is okay , insulation okay, individual panels testing and working within tollerances.

Inverter is set to G83 and all UK settings checked and confirmed correct.

What could I be missing?

There dosent seem to be any pattern to the tripping, stays on for several days but will then trip out for hours until the client turns off the array.

Thanks all

Tony
 
Thinking of it, it usually is in the rain that I get the call that its happened but the array is not earthed so wouldnt see how this could effect the RCD.


Am going back to site today so will upgrade to 4mm T+E but cant see how this will have an effect.

I need the 30mA RCD as have dropped the cables through a stud wall so need the protection.
 
You do not say what the rcd arrangement or value is, however:
- installation manual says rcd 100mA minimum
- inverter should not be sharing the rcd with any other circuits, particularly ones where the rcd is there for additional protection (ie cables buried in walls)
- whether Fronius TL can use ordinary type AC rcds rather than Type A or Type B I do not know (I use SMA and Power-One mostly)
 
You posted while I was typing.
4mm will not affect the rcd issue that will only affect the voltage drop
30mA is likely to be the problem - read the installation manual.
SWA in stud wall might be the answer
 
I agree with Bruce and would also add that you should really be earthing your array as you are using a transformerless inverter.
 
You can't put a transformerless inverter on an RCD shared by anything else or you will often get this problem, no substitute, put the inverter on it's own RCD, ideally you mechanically protect the cable in the stud wall and connect without an RCD.
 
I did hear a rumour (not checked cos I'm too busy!) that the new guidance stated that a transformerless inverter now only needed an earth if the array could be touched (through a velux for example).
2.5mm cable is inadequate for this set up, 4mm minimum because of voltage drop, maybe even 6 (thats what the 4000tl needs)
I have got away with 30ma RCD on a seperate garage board (may be wortha try) or changing to a different type of RCD but otherwise it has to be a 100ma.
 
Last edited by a moderator:
You posted while I was typing.
4mm will not affect the rcd issue that will only affect the voltage drop
30mA is likely to be the problem - read the installation manual.
SWA in stud wall might be the answer

There is a new type of cable easier to use than SWA - comes under the products name of pre-wired conduit by Nexan complies with BS8436, which is one of the cable types that doesn't need RCd protection when in a wall. There is also another manufacturer whos name escapes me at the moment. Looks and feels like FP.
 
all them TRIPS :) back costing money!bite the bullet run swa take off rcd!never have to go back unless you going to earth the array?
 
Swap RCD for a different make. I had this issue on one of my first installs. No faults and RCD tested out fine, swapped it anyway for same make and had same problem. Changed manufacturer and had no further problems (over a year ago).
I put a complaint into the manufacurer asking for any explanation but I never got got one. Worst thing is I cant remember what make it was now for sure. I've never had another do it since though.
 

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