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Discuss Increasing 3PH Supply? in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. -Matt
    Offline

    -Matt Regular EF Member

    Location:
    England
    A company i do work for are running over the capacity of their existing 100A 3PH supply, they are pulling around 100-120A all day long.

    I am trying to get them to get a bigger supply, they have tried asking for a 250A supply from the DNO, but they want £20K. (they reckon the transformer would need upgrading)

    Its an overhead supply, and a transformer (pole mounted) is only 15-20 metres away, on boundary of customer property.

    I don't know what size the transformer is, but its not the smallest I've ever seen, and only looks to supply 2 properties.

    Ive just had the thought of a second 100A supply, as it would be dead easy to split the demand across two supplies.

    Has anyone tried getting an additional 3PH supply? and was it more cost effective than a 250A supply?

    I guess it still comes down to if the transformer has capacity, but i find it hard to believe it would be maxed out with 2 properties?

    Cheers
     
  2. Pete999
    Offline

    Pete999 Trusted Advisor

    Location:
    Northampton
    Business Name:
    None
    Is the 120Amp just limited to 1 phase or are all 3 phases affected in the same way?
     
  3. -Matt
    Offline

    -Matt Regular EF Member

    Location:
    England
    Its mostly 3Ph (no neutral) equipment, so all 3 phases, but well balanced.
     
  4. Pete999
    Offline

    Pete999 Trusted Advisor

    Location:
    Northampton
    Business Name:
    None
     
  5. westward10
    Offline

    westward10 In echoed steps I walk across an empty dream. Staff Member Trusted Advisor

    Location:
    Northamptonshire
    Is this 100-120A loading constant.
     
  6. TonyMitchell
    Offline

    TonyMitchell Regular EF Member

    Location:
    Berkshire, UK
    When we enquired about getting a 100a 3-phase supply a couple of years ago, SSE quoted a good price - around £1,700 - but it was conditional on surrendering two separate 100a singles that we have.
     
  7. Vortigern
    Offline

    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    Presumably the equipment is motor equipment? Is the equipment rating in total matching the amount being pulled. I suppose you are using a clamp meter? Is there signs of thermal damage?
     
  8. davesparks
    Offline

    davesparks Trusted Advisor

    Location:
    guildford
    Have you asked them what size supply it would be possible to get without an upgrade of the transformer?

    Is there a planned increase in the current load, as you’ve requested a supply just over twice the current demand I assume there must be?

    They almost certainly won’t give you a second supply in to the same installation, especially not such small supplies.
     
    • Like Like x 1
  9. davesparks
    Offline

    davesparks Trusted Advisor

    Location:
    guildford
    How has the demand been measured, by instantaneous readings with a clamp meter or by a load study over a period of time?
     
  10. TonyMitchell
    Offline

    TonyMitchell Regular EF Member

    Location:
    Berkshire, UK
    A cost effective option may be to request an additional 100A single phase supply and separate some/all of the SP loads off the TP board, to bring its load down under 100A. Assuming the DNO will allow you the additional SP supply, of course.
     
  11. Andy-1960
    Offline

    Andy-1960 Electrician's Arms

    Location:
    Wolverhampton
    What is the power factor, you may be able to reduce the current being drawn by installing some power factor correction equipment.
     
    • Like Like x 1
  12. dmxtothemax
    Offline

    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    Have you asked DNO how much more you can safely pull from the existing transfomer ? You may be able to go to say 150A, that would be a simpler cheaper option.
     
  13. marconi
    Offline

    marconi Regular EF Member

    Prompted by davesparks good idea of a load study, could you tell us please what major equipments are responsible for the lion's share of the load current and whether they are on all the time or scheduled? I am wondering whether the client might be interested in an energy audit to see if he can achieve the same business outputs using less energy (load current) either by changing the way the equipments are used or controlled or by investing in new equipments or sub-systems of them. After all 415 x 1.73 x 120 = 86kW so 86 x 8 hr working day = 688kWh or 86 x 24hr(all day long) = 2064kWh.

    688 x 13p/kWh costs £90 a day(£33k) and 2064kWh costs £270 a day(£99k). (Figures in brackets over 365 days)

    If say 10% could be saved in energy that's £3k a year or £10k a year reduction in cost for 8hr or 24 hr usage respectively

    Updating air compressors, process heating, HVAC, refrigeration plant and lighting (or their control) are candidates for 'spend to save'. I have no experience of the magnitude of typical savings but 10% does not seem unrealistic to me.

    Just some thoughts to go in the melting pot on a different approach to spending £20k and achieve the same end.
     
    • Like Like x 2
  14. bigspark17
    Offline

    bigspark17 Electrician's Arms

    Location:
    wales
    In my experience the DNO will not put 2 seperate supplies into same buildng, especially a small one.
    Why not upgrade to 150/160A amp this may be surprisingly affordable compared to the 20k 250A supply
     
  15. plugsandsparks
    Offline

    plugsandsparks Electrician's Arms

    Location:
    Chesterfield
    I have been managing a 80amp TP supply, as the DNO want £55K to upgrade !!!.

    The ideas already suggested have worked so far, these are.
    1. LED lighting throughout, thats low bays, security and office.
    2. PFC (didn't offer much, but i know some other installations can benefit substantially, so worth a visit.
    3. Gas supply was easy to upgrade so all electric hot water and electric heating was removed, new combi installed to supply hot water throughout.
    4. 3 X ammeters installed so manager can keep an eye on it and manage machines in sequence so to smooth out peaks.
    5. Most machines have VSD which has a huge impact on start currents.

    So far, clients supply hovers around 80 but now rarely goes over, often it is much less.
    Hope this helps
     
    • Informative Informative x 3
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