RCD's not tripping with TL transformers | on ElectriciansForums

Discuss RCD's not tripping with TL transformers in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

Joined
Mar 11, 2010
Messages
689
Reaction score
77
Location
Midlands
HI all,

getting some info though that there is problems with Transformer less Inverters and RCD's not tripping.

thought id check one of mine and low and behold it didnt trip.

It is the first time ive tested it with the PV on though so i would never normally pick it up. Looks like the the Inverter is injecting DC into the RCD toroid and saturating it.


ill try and get some more info as this now has gone above my head lol

Cheers
Crofty
 
I don't think he is talking about earth loop tests.

I'm actually surprised about this as it isn't something that has happened to us on the few installs we have carried out on RCD protected installations. What inverter are you talking about?

I'd be interested to hear if any other installers have had this issue. This is going to open the 'What RCD type do I need for TL inverter' debate once again I would imagine. The general consensus is that a type B RCD is only required if the inverter can inject DC currents into the AC side of the inverter. The reason being that it would not operate with standard RCD types in this scenario. But surely this is only under fault conditions and I've yet to see an inverter that isn't protected from this kind of issue anyway.
 
I know that
if you inject DC into a rcd it woont trip
thats why when you have to test for earth loop on an rcd circuit you use trip lock.
trip lock injects DC current to prevent rcd from tripping
:32::32::32:
 
What inverter are you having a problem with? I tried connecting my 8000TL to the wrong side of the rcd recently and the rcd still worked fine on the trip time test at x1/2, x1 and x5 (0 & 180 in each case) whilst the inverter was outputting.
 
Last edited:
It was a Eversolar 4000TL, it seems to be tripping now, i didnt test it the apprentice did, seems ok for me, now im wondering if he did it properly which he said he did, and it is set to do all tests automatically. i thought id try it as this problem arose on another forum.

Cheers
Grand
 
Yes, it is being discussed on the Navitron and IET forums. Do Eversolar give the same assurance as SMA and Power One that their TL inverters cannot by design inject dc into the grid? I have never used Eversolar.
 
To answer my own question, the Everolar instructions for the TL3000-TL6000 I found online (albeit canadian version) specifical state that if an rcd is connected on the supply side then it must be a type b. So it looks like they can leak dc which would impede the operation of a normal type ac rcd found in most consumer units in UK.

Edit: Also found the UK instructions for the TL1700 and TL2000 inverters. Surprisingly the word "rcd" does not appear anywhere in the installation instructions. What they do say is:
"5.6.7 DC current injection monitoring
The Eversol is integrated with DC current injection monitoring unit. The DC output current at the AC terminals shall not exceed 0.5% of its rated output current of 5 mA, whichever is the greater."
I think the second 'of' is a typo and should read 'or'. At 2kW output, then 0.5% comes to 43mA of dc I believe. I doubt that is good for a type ac rcd, but do not know their resilience.

Makes me glad I have always used European inverters!
 
Last edited:
Normal running for Eversolar. SMA and Power One say theirs can't by design inject dc to grid. Have not looked up other manufacturers.
 
Last edited:
You learn something new every day - I always thought it was something that could happen under fault conditions only.
 
Last edited by a moderator:

Reply to RCD's not tripping with TL transformers in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

News and Offers from Sponsors

  • Article
Join us at electronica 2024 in Munich! Since 1964, electronica has been the premier event for technology enthusiasts and industry professionals...
    • Like
Replies
0
Views
352
  • Sticky
  • Article
Good to know thanks, one can never have enough places to source parts from!
Replies
4
Views
901
  • Article
OFFICIAL SPONSORS These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then...
Replies
0
Views
1K

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top