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Thread: Outdoor trench

  1. #11
    Join Date
    May 2012
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    Quote Originally Posted by ramsy View Post
    Another forum member NewtonLaw is more familiar with an Electromagnetic-Transient Program called Cyme
    Thanx, i'm going to send him private message & share with you the feedback or i'll ask him to join our thread.
    "Have a nice day"

    Sleem

  2. #12
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    Quote Originally Posted by m sleem View Post
    But, i'm still meeting the requirements of 800.133(a)(2) since we have approx 500mm distance from telecom to 13.8kv feeders, may be i'm not meeting TIA/EIA where >600mm shall be maintained but it's ok from NEC requirements.
    Please advise, thanks in advance.
    "Have a nice day"

    Sleem

  3. #13
    Join Date
    Jul 2005
    Location
    LA basin, CA
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    1,542
    Quote Originally Posted by m sleem View Post
    But, i'm still meeting the requirements of 800.133(a)(2) since we have approx 500mm distance from telecom to 13.8kv feeders, may be i'm not meeting TIA/EIA where >600mm shall be maintained but it's ok from NEC requirements.
    I don't believe Proximity to 13.8kv distribution voltages is addressed by this section, or anywhere else in NFPA-70.

    I believe 800.133(a)(2) concerns proximity to "electric light, power" & Class-1 control circuits.

    I believe "electric light, power" may be up to 277vac, while 725.41 A) Class 1 Power-Limited Circuits. are not more than 30 volts and 1000 volt-amperes.
    Roger Ramjet NoFixNoPay

  4. #14
    Join Date
    Nov 2016
    Location
    Honesdale, PA USA
    Posts
    63

    CYME and EMPT

    Quote Originally Posted by m sleem View Post
    Thanx, i'm going to send him private message & share with you the feedback or i'll ask him to join our thread.
    Hello. We worked for a number of years with our local Public Utility Commission to revise their requirement to have one trench with all the utilities in it. This included Gas, water, phone and Data circuits and cable TV in vertical configuration with no requirement for separation between power system cables (any Distribution voltage) and phone/Data and Cable TV/Data cables. It did not take long before all the utilities responded with technical details as to why this was not a good idea. As mentioned in your threads, noise, ground currents, inductive interference, fault current coupling, etc. all provided various operational concerns. To be sure, these items are always a concern however, locating cables on long runs intentionally exacerbates these concerns to unacceptable levels not to mention the mechanical difficulties attempting to perform repair or cable locating services.

    In any case, separation between power cables and most anything else remained in effect. As to your questions regarding transient analysis, two programs are available and are very well written to power system analysis. EMTP (Electro Magnetic Transient Program) ( see https://www.youtube.com/watch?v=P6k1X9T0ccs and https://www.epri.com/#/pages/product/1000366/ ). This is a powerful program that allows you to model your system and test the various operating scenarios for transient response and more. You will have a step learning curve but it is worth the effort. I believe version 4.0 is free if you are an EPRI member, may be free to the public.

    The second program for power system analysis is CYME from Copper Power Systems now EATON. This software allows the user to analyze Distribution systems, Transmission systems, cable ampacity, coordination studies, grounding grid design, network load flows and includes EMTP. (see http://www.cyme.com/software/ )

    These are the programs I used and have been very pleased with their results. Hope this helps.

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