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Thread: Class 1 Division 2 12VDC to 24VDC Power Supply

  1. #1
    Join Date
    Jan 2007
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    5

    Class 1 Division 2 12VDC to 24VDC Power Supply

    Greetings ladies and gents. I'm looking for a class 1 div 2 power supply, 12VDC input to 24VDC output at 2A, for a remote location control system. Can anyone recommend such a device?
    BTW, what agency actually dictates Class 1 Division 2?? OSHA? NFPA? THANK YOU, H.

  2. #2
    Join Date
    Jul 2004
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    Texas by the Gulf, geat crab, great shrimp
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    Quote Originally Posted by bachrachh View Post
    Greetings ladies and gents. I'm looking for a class 1 div 2 power supply, 12VDC input to 24VDC output at 2A, for a remote location control system. Can anyone recommend such a device?
    BTW, what agency actually dictates Class 1 Division 2?? OSHA? NFPA? THANK YOU, H.
    Where does the 12VDC power supply originates from? Series connection of two independent 12VDC power sources will produce 24VDC. Siemens SITOP power supplies are listed for Class I, Dv. 2 use, but mostly with AC input.

    Both NEC and OSHA addresses the requirements for Hazardous Location Installations. To define an area you can seek guidance in NFPA 497.

  3. #3
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    Jan 2007
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    12VDC to 24DVC

    Thank you for the reply. This unit is a remote location compressor for natural gas. The compressor is powered by a Kubota diesel converted to run off of the well gas. The alternator and starter are both 12V and explosion proof - read expensive and special order. The starting battery provides the 12VDC control power. The control PLC and HMI are 24VDC. Simplest manner to get 24VDC has been to use a power converter. Gas field operator is now requiring a redesign to use all Class 1 Div 2 devices, hence the search. Adding another battery to get 24VDC means changing out the alternator and starter or some type of isolator / relays / batt switching unit (can I get those in class 1 div 2?) and major expense. Simplest fix is to find the converter if it exists.... Thanks, H.

  4. #4
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    Quote Originally Posted by bachrachh View Post
    Thank you for the reply. This unit is a remote location compressor for natural gas. The compressor is powered by a Kubota diesel converted to run off of the well gas. The alternator and starter are both 12V and explosion proof - read expensive and special order. The starting battery provides the 12VDC control power. The control PLC and HMI are 24VDC. Simplest manner to get 24VDC has been to use a power converter. Gas field operator is now requiring a redesign to use all Class 1 Div 2 devices, hence the search. Adding another battery to get 24VDC means changing out the alternator and starter or some type of isolator / relays / batt switching unit (can I get those in class 1 div 2?) and major expense. Simplest fix is to find the converter if it exists.... Thanks, H.
    You can just install a parallel battery bank, then connect the output of the batteries in series. Blocking diodes all over of course and the recharging time will be increased. The crudest way to deal with it is to put all your non-Ex rated stuff into XP boxes or even locate those away from the Div 2 area. 5-20' away and 2-3' above grade level should put you outside of the classified area. So first define the extent of the Div. 1 and Div. 2 bubbles.

  5. #5
    Join Date
    Jul 2009
    Location
    Denver, CO
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    7
    bachrachh - I think Weidmuller might have a DC boost converter, but you'd need to check the specs for compatibility.

    How many of these systems are you doing, and what is your timeframe? If you don't find a product already on the market, please contact me off-board, and we might be able to help you out. We have a product on our list of mothballed engineering projects that would probably work for you. If you can wait until spring to install certified product, and you need enough of them that between your business and the expected business of others we can cover our costs then we might be willing to take it through certification.

    Also, check your PLC. I know that some PLCs intended for SCADA systems, such as a few made by Control Microsystems (and one we have in development but haven't released yet) have built in 12->24V converters for I/O. Also, most PLC's and HMI's are spec'd to run just fine from 12V if you are not doing 4-20mA loops (including HART). What PLC and HMI are you using, and for what kind of I/O?

    Tim Kirk

    (Moderator’s Note: Edited to remove email address. If you wish to send an email message to this person, then first send a Private Message via this Forum, and ask for the email address.)
    Last edited by charlie b; 12-02-10 at 10:27 AM.

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