1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

One for the DNO folks

Discussion in 'Electrics UK' started by electronicsuk, 17 Apr 2010.

  1. electronicsuk

    electronicsuk

    Joined:
    7 May 2007
    Messages:
    3,316
    Thanks Received:
    275
    Location:
    Lincolnshire
    Country:
    United Kingdom
    Just a quickie. Someone asked me today; what is the largest 400v supply that the DNO will offer before insisting on a direct 11/33kV connection with to the ring with on-site customer transformer/switchgear? I don't know the answer, and I suspect the question may be a little too general to give a specific answer, but if anyone has answers that I could pass on then it would be much appreciated.
     
  2. Sponsored Links
  3. electronicsuk

    electronicsuk

    Joined:
    7 May 2007
    Messages:
    3,316
    Thanks Received:
    275
    Location:
    Lincolnshire
    Country:
    United Kingdom
    Also, does anyone think the topic views counter is broken? This has only been on here 10 minutes and apparently already viewed 1097 times...
     
  4. electronicsuk

    electronicsuk

    Joined:
    7 May 2007
    Messages:
    3,316
    Thanks Received:
    275
    Location:
    Lincolnshire
    Country:
    United Kingdom
    Answered my own question - the Central Networks site informs me that anything up to 275kVA is possible on CT metering, anything in excess of this will be part of the high voltage network.
     
  5. kai

    kai

    It depends on many factors, including the distance to local transformer substation, its capacity, and whether the existing network can cope with it.

    I once saw a dedicated cable being laid from the substation to a new block of flats, but the distance was only just over one hundred yards. :LOL: :LOL: :LOL:
     
  6. PrinceofDarkness

    PrinceofDarkness

    Joined:
    1 Jan 2006
    Messages:
    611
    Thanks Received:
    62
    Location:
    London
    Country:
    United Kingdom
    Hello Matthew, yes. your question is a little too general for a specific repy...

    During my long stay with LEB, we often set the limit at 300A per phase for 3ph, LV cutouts. But during a shorter time with the EEB the limit was set at 200A per phase. In either case, it was subject to the main feeder cable's ability to handle the load along with the other local loads.



    Lucia.
     
  7. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,506
    Thanks Received:
    405
    Location:
    Devon
    Country:
    United Kingdom
    We maintain a site with a 552kVa supply which is supplied by a dedicated DNO sub.

    We do some work on a site which has private subs around the site, with private 11kv switch gear.............the maintenance of which is contracted out the DNO :LOL:
     
  8. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,506
    Thanks Received:
    405
    Location:
    Devon
    Country:
    United Kingdom
    I have also worked on a site with a 1200amp TP incomer - Thats 828kVa. Again, DNO ownered and operated sub and supply.
     
  9. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,506
    Thanks Received:
    405
    Location:
    Devon
    Country:
    United Kingdom
    The more I think, the more I recall.

    Here is a 500amp TP supply on an old site, replaced by an 800amp TP supply not so long ago. All DNO installed and operated.

    Grey chamber in center is the incomer, green cabs to left are CT metering and documents, green MCCB board to right is a good old Ottermill.

    [​IMG]
     
  10. Sponsored Links
  11. ricicle

    ricicle

    Joined:
    14 Sep 2006
    Messages:
    6,343
    Thanks Received:
    382
    Location:
    Gloucestershire
    Country:
    United Kingdom
    I seem to remember that 600A was the biggest LV supply that a local REC would supply from their LV network.
    Our old place needed 4-5 MW and was supplied via 6 off 1000kVA Tx's.
    Most medium size industries will have 11kV on site whether it be their own or the REC's switchgear. Some heavy industries transform from 33 or even 132kV
     
  12. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,506
    Thanks Received:
    405
    Location:
    Devon
    Country:
    United Kingdom
    This is a TP 1200amp supply from a dedicated sub. It is DNO owned and installed.

    The galv conduit carries a pair of 2.5mm singles which are switched by the DNO volt free terminals in the customer accessible box on the side of the CT chamber. They are used to switch the contactor for the OP heating in the offices. Only switches immersion heaters and toilet heaters now, most of the storage rads have gone to make way for air con.

    [​IMG]
     
  13. johno12345

    johno12345

    Joined:
    9 Feb 2005
    Messages:
    299
    Thanks Received:
    5
    Country:
    United Kingdom
    we used to have 2 800 amp supplies fed from a transfomer which also fed local distribution
     
  14. electronicsuk

    electronicsuk

    Joined:
    7 May 2007
    Messages:
    3,316
    Thanks Received:
    275
    Location:
    Lincolnshire
    Country:
    United Kingdom
    Thanks chaps. It looks as if larger supplies may be possible, but on the site of the DNO for the area concerned, they state in black and white that 275kVA is the largest they will run for a new supply. I'll advise that they need to contact the DNO themselves for a more specific answer.
     
  15. mfarrow

    mfarrow

    Joined:
    2 Nov 2009
    Messages:
    2,126
    Thanks Received:
    244
    Location:
    Warwickshire
    Country:
    United Kingdom
    Sounds about right, they wouldn't want you to use up all their spare capcity now, you they?!

    Yes, it will depend on the engineer doing the quote, the spare capacity on the system, and the DNO's own guidelines.

    Sometimes the DNO might insist on giving you a substation just because there isn't the capacity there on their 400V network. This is costly, but you really have no choice!

    I recently however managed to procure a 200kVA supply at 400V where the DNO had originally insisted on a substation. We couldn't give them the land for this, so I convinced the engineer to quote for upgrading one of their existing subs. It was costly (60% extra!) but just lets you know it's possible.
     
  16. efiste2

    efiste2

    Joined:
    14 Apr 2007
    Messages:
    492
    Thanks Received:
    33
    Country:
    United Kingdom
    Im not sure about the agreed capacity, but I know for a fact that we install many twin 500kva transformer substations for large consumers that are fed via 4 fuseways each fuseway having 3 x 315 or 400A HRC fuses. Anything above that then im pretty sure Scot-Power insist on a HV supply.
     
  17. geraint

    geraint

    Joined:
    28 Aug 2008
    Messages:
    1,710
    Thanks Received:
    24
    Location:
    Hampshire
    Country:
    United Kingdom
    sounds like a case for batman and robin.... but they seem very quiet tonight... :LOL:
     
Loading...

Share This Page