Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. Gragas

    Thermal conductivity/resistivity of concrete used for the encasement of underground electrical ducts

    You have to be careful using that annex. The true answer is to use software similar to ETAP or similar to create a model in order to accurately model the actual configuration you are going to use. Otherwise, I can tell you that all of the derates that occur if you followe the descriptions to a...
  2. Gragas

    EE exam topics

    You can take a look at: http://www.compleximaginary.com/ Its a Power PE exam prep website. Dont be too spooked as basic principles of a lot of things is what the PE exam is about. That site has several very good youtube videos that go over basic concepts and problems, and how to work them...
  3. Gragas

    Arc Flash Detection

    Its larger drop than you would think. I have never seen a light detection scheme were the detection isn't easily routed through the compartments. Also, I do not diagree there is a bunch of empirically derived factors. However, the "reliance" is typically strictly dictated by Plant safety...
  4. Gragas

    Arc Flash Detection

    Light detection relays are typically fairly cheap and are indeed faster, thus typically reducing arc flash levels. Arc Maint switches are also useful and extremely cheap. Bus differential is fast, but I disagree it does a "far better job". Its also typically more expensive. Bus diff used...
  5. Gragas

    Should a Dry Type Transformer be mounted inside or outside of electrical enclosure?

    If you are referencing something around 3MVA dry type transformers, a couple other items do consider: - You can typically close couple and save yourself cable/non-seg connections - No reason to have a NEMA 3R if its inside the building - Can make connecting HRG very simple. - No foundations...
  6. Gragas

    Neher McGrath Typical Value for Concrete

    Not sure why, but I am glad it is... the derates would hurt.
  7. Gragas

    MCC Bus Bar Bracing

    If you are going to try that Waross, depending on cable size wouldnt it be an option just to have a 480-480 transformer in that feed? Random bonus of possibly helping loadflow? ha
  8. Gragas

    Surge Arrestor - 3 Wire Medium Voltage System

    There are several standards for surge arresters that should get you where you need to go.
  9. Gragas

    To locate an existing grounding system?

    The fact that he cannot find the grid is not due to inexperience if you don't even have the original drawings. Even a guy with 50 years of ground grid design is still stuck in the same spot without drawings. Its a pure guess and a bad path to head down.
  10. Gragas

    Electrical loads and fan assisted transformers

    Depends on the application really... As a general design standard? No, I am not a big fan. (no pun intended) Depending on the type of plant and the overall system design, believing that you will not be adding to that power feed over the life of a plant is not a smart idea. Also, the design...
  11. Gragas

    Fault current calculations

    The structure and information in your question shows you should probably not be doing this unsupervised :P
  12. Gragas

    Switchgear Replacement Planning

    My main concerns would be, after your cable ideas: 1) C&I cabling is a huge concern. The small misc cabling within the gear can be a huge time sink if done poorly. Verify vendor point to points, track any cabling that will cross shipping splits for the gear (as they will need to be...

Part and Inventory Search