Question Regarding a RCD on 3 Phase, with a single phase sub-circuit

[Magwych]

I am installing a micro-brewery in our barn in France; as you can guess that, means that I am a brewer, not an electrician I did 'fess up to being a DIYer when signing on.
The brewhouse runs on 3-phase, both for the 12kw heating elements and for the pumps. All use a delta configuration i.e. 3 phases, no neutral.
ENEDIS, the national electricity network company has agreed to supplying me with a 36kVA 3-phase supply. I am organising the distribution panel and wiring, once installed our local electrician will give it a check over and then arrange for inspection and a certification check. I am trying to reduce both costs and especially waiting time.
My question is regarding the nature of RCD operation in 3 phase circuit...Bear wih me, here it comes ...
I want to have a RCD dedicated to the brewhouse. The hot liquor tank has a temperature controller, which is itself a low voltage (12V DC) unit. The temperature controller has a 220V AC-12V DC power supply, powered by L1 and N on the supply. It operates a 230V solenoid switch to regulate the power to the heating element.
Finally: Will the presence of a 2A load on L1/N create an imbalance on the phases that will cause the 30ma RCD to trip?

I hope this picture avoids a thousand words :

 

[Megawatt]

I am installing a micro-brewery in our barn in France; as you can guess that, means that I am a brewer, not an electrician I did 'fess up to being a DIYer when signing on.
The brewhouse runs on 3-phase, both for the 12kw heating elements and for the pumps. All use a delta configuration i.e. 3 phases, no neutral.
ENEDIS, the national electricity network company has agreed to supplying me with a 36kVA 3-phase supply. I am organising the distribution panel and wiring, once installed our local electrician will give it a check over and then arrange for inspection and a certification check. I am trying to reduce both costs and especially waiting time.
My question is regarding the nature of RCD operation in 3 phase circuit...Bear wih me, here it comes ...
I want to have a RCD dedicated to the brewhouse. The hot liquor tank has a temperature controller, which is itself a low voltage (12V DC) unit. The temperature controller has a 220V AC-12V DC power supply, powered by L1 and N on the supply. It operates a 230V solenoid switch to regulate the power to the heating element.
Finally: Will the presence of a 2A load on L1/N create an imbalance on the phases that will cause the 30ma RCD to trip?

I hope this picture avoids a thousand words :
View attachment 55870

Mag welcome to the forum and you can have your main breaker in your switch gear to be RCD and I wouldn’t think that the 12vdc controller at 2 amps is not going to trip your main breaker, it’s just another load. Good luck

 

[James]

Pathetic diagram shows a 3 phase rcd unit.
This compares the combined phase currents and compares the sum of them to the neutral current.

Out of balance current will not trip the rcd unless there is a fault to earth.

In brief, your diagram looks ok to me.

Edit,
The wiring to the 12v psu is wrong, I am sure you intended to connect it to live and neutral, however you have not.

 

[Magwych]

Pathetic diagram shows a 3 phase rcd unit.
This compares the combined phase currents and compares the sum of them to the neutral current.

Out of balance current will not trip the rcd unless there is a fault to earth.

In brief, your diagram looks ok to me.

Edit,
The wiring to the 12v psu is wrong, I am sure you intended to connect it to live and neutral, however you have not.

Thanks for the reply, I am sorry that my hand drawn diagram is not up to standard ;-)

Yes, that is meant to be a 3-phase RCD, it is a 3-phase installation. Tou are wuit right about the PSU, it is on the wrong side of the contacts for the eletcrically operated switch. I will amend my copy
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Mag welcome to the forum and you can have your main breaker in your switch gear to be RCD and I wouldn’t think that the 12vdc controller at 2 amps is not going to trip your main breaker, it’s just another load. Good luck

Thank you, Megawatt. I was concerned that with one phase out of balance and neutral only being used on the PSU the RCD would see a 2A difference between phase 1 and the other two. I admit that other working as an earth leakage detector I do not know what else the RCD does.
I will also be splitting the phases, before that particular RCD, to provide 3 radial socket circuits and 3 lighting circuits. i.e. one socket and one lighting cicuit per phase. Each phase with its own RCD befoe the socket and light MCBs. I could just as easily power the PSU from one of those socket circuits.

 

[Megawatt]

Thanks for the reply, I am sorry that my hand drawn diagram is not up to standard ;-)

Yes, that is meant to be a 3-phase RCD, it is a 3-phase installation. Tou are wuit right about the PSU, it is on the wrong side of the contacts for the eletcrically operated switch. I will amend my copy
[automerge]1582121285[/automerge]

Thank you, Megawatt. I was concerned that with one phase out of balance and neutral only being used on the PSU the RCD would see a 2A difference between phase 1 and the other two. I admit that other working as an earth leakage detector I do not know what else the RCD does.
I will also be splitting the phases, before that particular RCD, to provide 3 radial socket circuits and 3 lighting circuits. i.e. one socket and one lighting cicuit per phase. Each phase with its own RCD befoe the socket and light MCBs. I could just as easily power the PSU from one of those socket circuits.

Good luck and let us know if you need anything else. Have a great day

 

[James]

oh my god, I do apologise.

I didn't type the word pathetic. I started typing and the curser moved I think auto correct might have stuffed me up.

the diagram is good and clear. i could understand it just fine and i think the psu wiring was just an oversight.

once again, sorry for my awful typo.
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[DPG]

Best auto correct I've seen for ages

 

[Magwych]

oh my god, I do apologise.

I didn't type the word pathetic. I started typing and the curser moved I think auto correct might have stuffed me up.

the diagram is good and clear. i could understand it just fine and i think the psu wiring was just an oversight.

once again, sorry for my awful typo.
[automerge]1582124741[/automerge]
View attachment 55883

Thanks James/ I thought that was a "strng" reply, but I have seen far worse

 

[OnlQQker]

Brewery? What like beer brewing?

I would keep your address quiet if I was you Op, you will have a boat load of sparkys on your doorstep by tomorrow morning!

 

[DPG]

Hope we get free samples.

 

[Lucien Nunes]

Will the presence of a 2A load on L1/N create an imbalance on the phases that will cause the 30ma RCD to trip?

No, as per James it's fine. Note carefully the distinction between:

'Imbalance' in the context of three phases, meaning that the loads on the three lines are not all equal, and
'Imbalance' in the context of an RCD, meaning that not all the current that passes through the RCD to the load, returns through the RCD to the supply.

Any imbalance between the loads on the phases, such as your single-phase PSU, creates neutral current to the amount of the difference. Since the neutral conductor also passes through the RCD, this exactly compensates for the imbalance between the lines as far as the RCD is concerned. The RCD has no sense of the currents in the individual conductors, only the algebraic sum of them all. If that is zero, the circuit is not leaking and all is well.