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Thread: CID2 TRANSFORMER

  1. #1
    Join Date
    Sep 2016
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    Longmont, CO
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    CID2 TRANSFORMER

    Does a transformer have to have any specific ratings for use in a Class I Division 2 rated area?
    Per 501.100B it just refers to 450.21-27 which doesn't lead me to the conclusion that the transformer needs to be specifically rated for CID2.
    What about surface temperature? Seems like the requirements of 500.8 should apply, but I'm not confident how to do so.
    The application is a small (2-5KVA) encapsulated transformer in a CID2 analyzer room with LEL detection and adequate ventilation.

  2. #2
    Join Date
    Aug 2004
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    Northern illinois
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    16,895
    While it seems a little high of a rating to be a control transformer control transformers for use in CID2 are covered in 501.120.

    take a look at 500.8 (B)(3).
    Bob

  3. #3
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    Sep 2016
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    Longmont, CO
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    (3)
    Where specifically permitted in Articles 501 through 503,
    general-purpose equipment or equipment in general-purpose
    enclosures shall be permitted to be installed in Division 2 locations
    if the equipment does not constitute a source of ignition
    under normal operating conditions.

    I don't see where my situation is specifically permitted.

    I 've run into similar situations, and haven't been able to find a reason I can't use a general purpose transformer in a CID2 rated area.
    The surface temperature issue keeps me thinking.

  4. #4
    Join Date
    Feb 2003
    Location
    Illinois
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    501.100(B) does not require anything special for division 2 applications. Just like using a standard 3 phase motor in division 2. The only issue could be the temperature rise and the auto-ignition temperature of the products involved, but for most flammables that is not an issue.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  5. #5
    Join Date
    Jan 2016
    Location
    Earth
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    6,049
    Quote Originally Posted by Jim1959 View Post
    (3)
    Where specifically permitted in Articles 501 through 503,
    general-purpose equipment or equipment in general-purpose
    enclosures shall be permitted to be installed in Division 2 locations
    if the equipment does not constitute a source of ignition
    under normal operating conditions.

    I don't see where my situation is specifically permitted.

    I 've run into similar situations, and haven't been able to find a reason I can't use a general purpose transformer in a CID2 rated area.
    The surface temperature issue keeps me thinking.
    not sure what the haz substance is but generally you are talking about temps >400 F
    what makes you think that a xfmr will get that hot?

    std is 150 C, optional 80 or 115 C

  6. #6
    Join Date
    Mar 2013
    Location
    California, USA
    Posts
    67
    Yes, I think you can use a worst case 40C ambient + insulation rating of the transformer (which should have a hot-spot allowance) to determine a maximum transformer temp rise and thus surface temperature, then compare that to 80% of the AIT of the most volatile nearby product. Thoughts anyone?

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