Three Phase Board 230V

[Dizzy_Maskell]

Just after people's opinions seen this a few times and although not incorrect still makes me think:
Three phase board 8-12 ways usually linked out to run on a single 230V supply.
Seen second hand boards converted using bus bar to make in affect a 36 way single phase board.
Always have been properly done e.g labelled and all circuits ok but just wondered how common it is as I am coming across it in a few places now and seems a practical way of having loads of circuits in a single DB.
PS everything done safely correct circuit protection, earth loop etc

 

[Marvo]

Yep, triplens add up to load a shared neutral.

View attachment Schneider Harmonics and Transformers.pdf

This was the best I could find after a long day and at short notice.

 

[Silly Sausage]

That's a picture of the wife.
















Unfortunately, not mine!

 

[High Tower]

Double edges sword, it's no different to loading a TPN board with lots of single phase circuits across the phases! Your still going to have high neutral current.

I think you have to do a assessment of the environment in which it is to be used. I have single phased a TPN board before in the branch of an estate agents, however I'd never do it in say a factory or workshop!

 

[mark ju]

Sorry but fail to see where there is any confusion here. The op said about using a three phase board fed from a SINGLE phase supply. With the correct linking kit fitted this board becomes a single phase board. It's just as possible to overload a purpose made single phase board as a "converted" board. And as its fed from a single phase supply the load on the neutral conductor will be the same as the live.

 

[Knobhead]

Double edges sword, it's no different to loading a TPN board with lots of single phase circuits across the phases! Your still going to have high neutral current.

I think you have to do a assessment of the environment in which it is to be used. I have single phased a TPN board before in the branch of an estate agents, however I'd never do it in say a factory or workshop!

Sorry HT but not so, Using the calculation for resistive load the maximum neutral current could match the highest loaded phase.
So:
R = 20A
Y = 0A
B = 0A
N = 20A

Change the loading to say:
R = 20A
Y = 10A
B = 5A
N = 13.2A
But now we have the natural triplen at 150Hz in the wave form.

I tried to do a wave form drawing of the neutral current, all I managed to do was send myself cross-eyed.

 

[High Tower]

I stand corrected mate!, I'm not going to argue with that !!.

My sentiments still stand on assessment of environment.

 

[Knobhead]

Like anything our old friend diversity comes out to play and you have to play with it.

I’ve lost count of the 3 ½ core SWA’s I’ve put in, never had a problem with the neutral even 20 years later.

 

[High Tower]

Like anything our old friend diversity comes out to play and you have to play with it.

I’ve lost count of the 3 ½ core SWA’s I’ve put in, never had a problem with the neutral even 20 years later.

Never even seen one

 

[VoltzElectrical]

Sorry but fail to see where there is any confusion here. The op said about using a three phase board fed from a SINGLE phase supply. With the correct linking kit fitted this board becomes a single phase board. It's just as possible to overload a purpose made single phase board as a "converted" board. And as its fed from a single phase supply the load on the neutral conductor will be the same as the live.

That's just it. failure to read the OP properly. I have fitted a TPN board off a single phase supply with the conversion kit supplied from the same manufacturer of the board (Dorman Smith).

Jumping the gun again folks.

 

[netblindpaul]

Not quite jumping the gun, I responded to a post that was going off topic a little, I admit, which then sent the thread not just off topic a little, but it seems a LOT!
IF the board is correctly & fully single phased, then that is fine as mark ju has said, it is then simply say a 12*3, i.e. 36 or xx way 1ph DB, however, running just single phase loads across 3 phases on a 3ph db with a sub main etc. designed to take a 3ph load is not really OK.

 

[VoltzElectrical]

Not quite jumping the gun, I responded to a post that was going off topic a little, I admit, which then sent the thread not just off topic a little, but it seems a LOT!
IF the board is correctly & fully single phased, then that is fine as mark ju has said, it is then simply say a 12*3, i.e. 36 or xx way 1ph DB, however, running just single phase loads across 3 phases on a 3ph db with a sub main etc. designed to take a 3ph load is not really OK.

Of course is it not ok to run all loads on a 3 phase board across one phase. Basic electrical training would tell you that you would overload the neutral, just as balancing all 3 phase loads results in no load on the neutral at all. I just don't know why anyone assumed this was the case.

As I said, It's quite common on larger jobs to use a 3PN board with a single phase incoming supply and linking kit to give a larger capacity board.

smiley face.

 

[Knobhead]

Of course is it not ok to run all loads on a 3 phase board across one phase. Basic electrical training would tell you that you would overload the neutral, just as balancing all 3 phase loads results in no load on the neutral at all. I just don't know why anyone assumed this was the case.

As I said, It's quite common on larger jobs to use a 3PN board with a single phase incoming supply and linking kit to give a larger capacity board.

:winkiss:

Voltz this was the point is the point I was trying to get across.

The board may have been designed correctly but as I found to my cost extras do get added.

With me it was a common 115V control supply to 21 various panels. I used a 3Ph 24 way board as described above. A great big engraved label on the front “Primary Control Circuits ONLY”. The supply was end tapped so not suitable for power outlets.

All was fine when I left it and went on my wandering around the company for a year or so. I arrived back to be informed the 12.5KVA 433/115V transformer had caught fire and a new 17.5KVA installed.
The original 3 spare ways had sub-boards connected to them, all supplying power outlets. It wasn’t a big thing to put right, a new DP board fed off a centre tapped 433/115V transformer.
The stupid thing is the sub-boards were DP, surely the fact that they were fed off a SP+N board must have set alarm bells ringing?

Since then I’ve had a thing about “who will follow me” and so went totally off the concept of using boards in such a way.

Would have loved to have been there when the transformer caught fire, every section of the plant shut down at once.

The reason for the common control supply was simply to ensure each panel didn’t have different potentials on the control supply. All the panels were cross linked, the central desk had all 21 different control supplies on multiple feeds.


PS couldn't resist putting a smiley in the quote :38:

 

[GLENNSPARK]

That's a picture of the wife.
















Unfortunately, not mine!

it must be a dusk til dawn thing then...