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Author Topic: Electrics keep tripping since Solar PV install  (Read 1184 times)
Scruff
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« Reply #15 on: October 13, 2017, 12:28:40 AM »

The easiest way is to add a second consumer unit just for the PV right up against the existing unit. You can spur off the incoming mains.

How does that fix the problem?...

A 30ma RCD will trip with solar PV.

Is the PV RCD a 60mA or 30mA with less "power noise" on the PE?
...a case of...
Solar PV plus house on 30mA = problem
Solar PV 30mA = no problem
House 30mA = no problem
?
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eabadger
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« Reply #16 on: October 13, 2017, 08:22:07 AM »

http://www.circuit-protection.co.uk/latest-news/120-solar-power-installations--do-you-know-what-type-of-rccb-to-use-and-why
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Scruff
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« Reply #17 on: October 13, 2017, 08:39:30 AM »

http://www.circuit-protection.co.uk/latest-news/120-solar-power-installations--do-you-know-what-type-of-rccb-to-use-and-why


As the level of DC current increases the tripping time will increase to a point where the coil is completely saturated and the RCCB may not operate at all see clause 133.1.3


A type may not trip when you want then too. I don't think they nuisance trip from injected DC.
« Last Edit: October 13, 2017, 08:41:17 AM by Scruff » Logged
eabadger
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« Reply #18 on: October 13, 2017, 08:56:42 AM »

A type is pretty standard here, tested on my new metrel and does what it should.
i had type ac in to start and they nuisance tripped all the time, read up the rules, saw what the nz and aussis said as they seemed sensible about type B cost and went for type A, sorted.

http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=60270

the link i posted seems clear that type AC not permissible for pv, do installers change them to B or leave alone?
« Last Edit: October 13, 2017, 04:15:05 PM by eabadger » Logged

1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
rogeriko
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« Reply #19 on: October 13, 2017, 10:12:29 PM »

The easiest way is to add a second consumer unit just for the PV right up against the existing unit. You can spur off the incoming mains.

How does that fix the problem?...

A 30ma RCD will trip with solar PV.



You leave the original consumer unit/RCD to run the house and connect the PV to the new consumer unit with whatever RCD is neccessary for PV.


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eabadger
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« Reply #20 on: October 14, 2017, 08:12:06 AM »

why not just fit as the regs and manufactures seem to say, the correct type rcd, B if that is what is said, A if you read the NZ and aussie regs.

just read on siemens site type AC not allowed in Germany.
also new type F which is a new one for me.
my modulating water pumps used to trip the AC as they are thryristor controlled.

regs here say cooker supplies must be type A here as induction hobs cause nuisance tripping on type AC, looking it seems that is pretty typical europe over, ex uk.
« Last Edit: October 14, 2017, 08:21:18 AM by eabadger » Logged

1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Scruff
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« Reply #21 on: October 14, 2017, 11:29:25 AM »

Accademic question Steve.
Indeed it ought to be an RCCB
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Pat_
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« Reply #22 on: October 14, 2017, 06:48:27 PM »

I have been concerned about this for a couple of years.

I have a system which is able to avoid any RCDs, so have no problem.

However if it is deemed that the cable from the inverter needs protecting with an RCD at the Inverter end than the N at the inverter must be earthed or it will not work.

If then the system is fed via an rcd at the house end the rcd will trip because the N is connected to earth.

So at the house end the connection must be straight to the supply (not through the CU) to avoid tripping the house rcd.

However if it was deemed that the interconnecting cable needs an RCD at the inverter end then it would also need one at the house end (as current can be sourced at either end depending on whether the sun is shining) but this cannot work because the neutral would be earthed at both ends and both RCDs would trip.

Conclusion, the cable must be installed in such a way as not to require RCD protection.
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Scruff
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« Reply #23 on: October 15, 2017, 07:33:14 PM »

Anti-Islanding to the rescue.
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eabadger
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« Reply #24 on: October 15, 2017, 07:35:31 PM »

why not just fit the correct type rcd?
i cant believe installers dont?
and how can your pv bypass rcd, do you export all?
« Last Edit: October 15, 2017, 08:58:26 PM by eabadger » Logged

1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
jonesy
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« Reply #25 on: October 16, 2017, 10:20:13 AM »

However if it is deemed that the cable from the inverter needs protecting with an RCD at the Inverter end than the N at the inverter must be earthed or it will not work.
If then the system is fed via an rcd at the house end the rcd will trip because the N is connected to earth.
There are no circumstances where an on-grid consumer connects neutral to earth. Your statement is dangerous.

RCDs are an important additional protection that every house should have. They never nuisance trip. They trip because of incorrect selection, or a fault level near the trip point.
A tripping RCD should be investigated, tested and/or replaced. Just fitting a different type or a larger trip value without investigation is simply hiding the problem, degrading the protection, and increasing the chance of a belt.

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jonesy
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« Reply #26 on: October 16, 2017, 10:26:10 AM »

here in France type AC rcd are only allowed on resitive loads such as the immersion all others must be type A
Off topic Steve, but I don't think that's the case. A flyer from August 2016/nf15100 states a minimum of 2 RCD per installation, maximum of 8 downstream MCBs per RCD, type A (or F or B) for cooking appliances, washing machines or circuits destined for electric vehicles. All other circuits are to be type AC (or A or F or B)
type A are about 10% more expensive.
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eabadger
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« Reply #27 on: October 16, 2017, 01:05:13 PM »

from what i hear it is any circuit with dc component, cooker bit came about due to induction hobs?
pv is mandatory type B
our consumer unit is a 92 way!! with 4 rcds, but doesnt come under nf as off grid, but done to comply as we may one day be connected.
quick look on bricom man does show type a are more expensive, but was just a glance.
https://www.bricoman.fr/catalogsearch/result/?q=diff

steve
« Last Edit: October 16, 2017, 02:52:40 PM by eabadger » Logged

1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Pat_
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« Reply #28 on: October 16, 2017, 02:23:24 PM »

However if it is deemed that the cable from the inverter needs protecting with an RCD at the Inverter end than the N at the inverter must be earthed or it will not work.
If then the system is fed via an rcd at the house end the rcd will trip because the N is connected to earth.
There are no circumstances where an on-grid consumer connects neutral to earth. Your statement is dangerous.

RCDs are an important additional protection that every house should have. They never nuisance trip. They trip because of incorrect selection, or a fault level near the trip point.
A tripping RCD should be investigated, tested and/or replaced. Just fitting a different type or a larger trip value without investigation is simply hiding the problem, degrading the protection, and increasing the chance of a belt.



Um. Of course the N is connected to earth. At the point of supply (Sub-station transformer). If it weren't, the RCD would not work. And for a PME supply the earthing point is taken from the incoming neutral.  This is all rather basic stuff.
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Scruff
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« Reply #29 on: October 16, 2017, 05:29:47 PM »

RCDs are an important additional protection that every house should have. They never nuisance trip.

"In the second phase of the research, conducted in the UK, a preliminary report from the Council after testing 607 RCDs records a failure rate of 3.8%, dropping to 2.8% when RCDs that had been deliberately shorted out are removed from the sample."

"One in Italy where 21,000 RCDs were tested found 7% to be faulty. "


"This report describes the result of a field test of almost 1.000 Residual Circuit Devices, RCD, in Danish electrical installations. (The term RCD is used as a common reference for RCD type AC 0,03 A and RCD type A 0,03 A) The test showed that 7% of the RCDs did not work properly. It also showed a great difference between RCDs of type AC and of type A , as the error percentage for RCDs of type AC was almost 11%, while it was only 2,0% for the RCDs of type A."

I think 7% is the offical figure, 3.5% likelihood if you use the test monthly button monthly.

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