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  1. -Matt

    -Matt Regular EF Member

    Basically customer currently only has a 100A 3 phase supply, which is rather overloaded. Also has a 120KVA generator for a 55KW motor.

    Im trying to get a larger supply so everything will run off the grid and not overloaded.

    Ive spoken to the DNO in terms of trying to get a 400A supply.

    DNO has asked for a list of large motors, and starting method, which is:

    15KW motor 3 phase - S/D

    11KW motor 3 phase - Soft start

    36KW motor 3 phase - Soft start

    15KW motor 3 phase - S/D

    15KW motor 3 phase - S/D

    55KW motor 3 phase - Soft start

    Total power before diversity is around 180KW

    There is HV overhead lines onto customer property, with current 100KVA pole transformer.

    Was hoping for just a transformer change, along with new overhead cable, then 400A panel board etc at my end.

    However the DNO want to install a 500KVA ground mounted sub station at a cost of £50,000.........

    This seems rather excessive to me, and far more than the customer wants to spend...

    The DNO are telling me its because of the starting current of the 36KW and 55KW motor.
    They are using 164 starting amps for the 36, and 250A for the 55KW.
    This doesn't sound right to me on a soft starter.

    What do you guys think?
  2. snowhead

    snowhead Respected Member

    Maybe they've not noticed it says Soft start,
    Or more likely their calculations don't take allowance for soft start.
    Are these motors part of individual pieces of plant with random start, or making up a sequenced start system?

    And presumably they've built in some spare capacity for the transformer.
    • Like Like x 1
  3. plugsandsparks

    plugsandsparks Electrician's Arms

    You have asked for a 400A supply, £50,000 is normal price from DNO. Not seen them mount a big one on a pole
  4. Andy-1960

    Andy-1960 Electrician's Arms

    You could always ask for the option of just having an 11kv supply and your customer buy his own transformer.
  5. spinlondon

    spinlondon Forum Mentor

    Harlow Essex
    Get their own 11kV generator as well, and they could sell to the grid.
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