Discuss Substation Earthing Arrangment in the Industrial Electrician Talk area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
0
Hi All,
I have a question trying to understand earthing arrangments

SO,
We have a DNO Substation, 4 Core armoured Feeding the Distribution Board Fed from an Auxillary Transformer (Clients)

The DNO Substation has an Earthtape around the substation, which connects to the earthmat of the entire substation.

The Transformer, which supplies the Substation, Has a N-E Link, This Earth link goes directly to the Earth Mat.

The Main earth for the DB is supplied from the earth tape around the substation.

I would guess, this is a TT System,
However, The company i work for, says it is classed as a TNS System, As there is a separate Earth.
As it comes into the DB as a L1,L2,L3,N from the armoured - Then A Separate Earth To The DB (Via Tape/Earth Mat

Im just confused, and would like clarification
 
Hi All,
I have a question trying to understand earthing arrangments

SO,
We have a DNO Substation, 4 Core armoured Feeding the Distribution Board Fed from an Auxillary Transformer (Clients)

The DNO Substation has an Earthtape around the substation, which connects to the earthmat of the entire substation.

The Transformer, which supplies the Substation, Has a N-E Link, This Earth link goes directly to the Earth Mat.

The Main earth for the DB is supplied from the earth tape around the substation.

I would guess, this is a TT System,
However, The company i work for, says it is classed as a TNS System, As there is a separate Earth.
As it comes into the DB as a L1,L2,L3,N from the armoured - Then A Separate Earth To The DB (Via Tape/Earth Mat

Im just confused, and would like clarification
Who is the local DNO/DSO, most have publically available technicial documents relating to things like substation design, earthing and the like.
 
My thinking is it goes to an earth electrode on the ground (Earth Mat)

Yes but that's the substation N-E link, so provides the first T in the earthing system. If it was TT then the installation would be connected to another, completely separate, earth electrode.

In this case you have a N-E link referenced to earth via the earth mat and then a seperate earth conductor from there to the installation so it is TNS
 
I understand I think,
if that transformer was connected to 1 earth mat, and the DNO Substation was connected to its own earth mat
Then the DNO would be on a TT System

No that sounds like a potentially dangerous situation (assuming the 2 transformers are in close proximity)

A TT system has the transformer N-E link referenced to earth via an earth electrode and then the installation has a completely separate earth electrode with the only connection between them being via the mass of the earth.
 
Sorry there isnt 2 Transformers.

1 Transformer, N-E Link to Earth Mat 1
Transformer Feeds Substation with 4 Core SWA (B,Bl,Gr,N)
Substation Main Earth Connects to Separate Earth Mat

Is that then a TT System?

Thankyou for your help, I know it probably seems simple to you, I'm just trying to get my head around things
 
Sorry there isnt 2 Transformers.

1 Transformer, N-E Link to Earth Mat 1
Transformer Feeds Substation with 4 Core SWA (B,Bl,Gr,N)
Substation Main Earth Connects to Separate Earth Mat

OK I'm a little confused now, isn't the transformer one of the main components of the substation?

I'm not 100% up on correct terminology as far as that goes.

Unless the transformer is a long way away from the substation so that the earth electrodes don't interfere with each other I don't see how that could be anything other than a potentially dangerous situation.
 
Dunno if this document will help at all, might give a bit of clarity/insight.

Also look for 'ENA TS 41-24' and BS EN 50522, of which the former is based on.
 

Attachments

  • cp335---earthing-design-for-gp-substations-.pdf
    379.9 KB · Views: 10
OK I'm a little confused now, isn't the transformer one of the main components of the substation?

I'm not 100% up on correct terminology as far as that goes.

Unless the transformer is a long way away from the substation so that the earth electrodes don't interfere with each other I don't see how that could be anything other than a potentially dangerous situation.
So the set up of this site in particular

1 HV transformer
This feeds 2 Auxillary Transformers

Aux TX 1 has a Neutral earth link directly to an earth mat
This in turn feeds the DNO Substation with a 4Core SWA. Powers the substation dB.

Aux TX 2 feeds the customer substation main LVAC Board. This TX Has an earth to the earth mat, just not from the neutral bar.
This LVAC board has the N-E link done within the panel rather than the transformer. (earth directly to earth Mat which


My question is,
1) if the DNO has a separate earth Matt, to that of the customer earth mat, would that make the DNO a TT System and the Clients a TNS System ?

2) why would it be dangerous if they are both adequately earthed?
 

Reply to Substation Earthing Arrangment in the Industrial Electrician Talk area at ElectriciansForums.net

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

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock