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Thread: Standard transformer sizes

  1. #1
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    Standard transformer sizes

    Is 2500 KVA a standard size transformer, or does it jump from 2000 KVA to 3000 KVA?

    This would be a pad mounted, oil filled, exterior, 3 phase delta to wye transformer to go from 12 KV to 480 V.

    Steve

  2. #2
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    Refer to IEEE Std C57.12.00 for a list of preferred ratings, of which 2500KVA is listed.
    "Just because you're paranoid, doesn't mean they're not out to get you"

  3. #3
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    I don't have that standard, so thanks for saying 2500KVA is listed.

    Steve

  4. #4
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    Ok, then here you go

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    "Just because you're paranoid, doesn't mean they're not out to get you"

  5. #5
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    You should note that most sizes above 250 single phase and 2500 3 phase are often considered substation and not distribution transformers. They might not be as readily available, particularly in a padmounted configuration for instance.

    Jim T

  6. #6
    Yeah that is correct and try ordering one now and getting a delivery date of 50 to 60 weeks.

    Another thing is be careful when you put that 2500 on your system, fuse sizes will be large and you will need to make sure your coordination is correct all the way back to the substation.

  7. #7
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    Quote Originally Posted by jtester
    You should note that most sizes above 250 single phase and 2500 3 phase are often considered substation and not distribution transformers. They might not be as readily available, particularly in a padmounted configuration for instance.

    Jim T
    C57.12.00 is standard general requirements for liquid-immersed, distribution, power, and regulating transformers. Of which, a padmounted transformer is a distribution transformer. In accordance with C57.12.80, the term "substation transformer" is not considered standard terminology for power or distribution transformers. Perhaps you were meaning to have said, unit substation transformer; which, would include articulated unit substation, integral unit substation, primary unit substation, and secondary unit substation.

    A distribution transformer is for transferring electrical energy from a primary distribution circuit to a secondary distribution circuit or consumer's service circuit. The definition has nothing to do with size or type of transformer. C57.12.10 is for transformers from 750 through 100,000 KVA with no mention of function differentiation.

    The long and short of it, is that transformer are based predominanantly on function and type, and not necessarily on size. I can get a power transformer that is 2500KVA or larger, that is not a unit substation transformer. I can also get a unit substation transformer that is smaller then 2500KVA, and it is not a pad-mounted transformer, but used for distribution.

    Yes, pad-mounted transformers are usually 2500KVA and smaller in size, but a 5000 KVA transformer, can still be a distribution transformer, of which it may be a primary or secondary unit substation transformer type.
    "Just because you're paranoid, doesn't mean they're not out to get you"

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