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Recent content by rezaa

  1. rezaa

    Car truck dicharge current

    I mean what saftware can I use. Can I use HIFREQ moudle of the CDEGS program to modle? Should I model the truck as 6 grid math which are commected to each other?
  2. rezaa

    Car truck dicharge current

    How can I calculate a discharge current for a car (truck) which is located underneath of a transmission line(230 kV)?
  3. rezaa

    Equipotential zone

    A galvanized steel seems to have higher resistivity with respect to copper.
  4. rezaa

    Equipotential zone

    This gradient control mat is for an air breaker switch for a 138 kV transmission line. I was told that the main reason for installing below the surface soil is to keep away from stealing those coppers.
  5. rezaa

    Equipotential zone

    By installing below the sufrface of the soil, we can reduce the touch voltage level.
  6. rezaa

    Equipotential zone

    To etablish an equipotential zone, a ground mat should be installed under the operation area of equipment and then connctect the mat to main grid. My question is that where the mat should be installed on the surface of the soil or below the sufrface of the soil. What are the difference between...
  7. rezaa

    Modeling Distribution Lines USing CDEGS software

    How far do we need to model the distribution lines in Malz, Hifreq module of CDEGS software? What is base for end points in the distrbution lines when we model?
  8. rezaa

    Step Potential Higher than Touch Potential ?

    The software calculate the potential difference between the ground potential rise (GPR) and the nearest conductor as touch voltage.
  9. rezaa

    California Professional Examination, Civil

    Take a look at the follwing document. http://www.iacforum.org/pdfs/Licensure72403.pdf
  10. rezaa

    Substation Grounding Design (Soil Resistivity model-3 layers)

    The FOP that uses the soil model can be resulted in lower or hihger grid impedance. So a realastic soil model is imporant in the calculation of the grid resistance.
  11. rezaa

    Substation Grounding Design (Soil Resistivity model-3 layers)

    The soil resistivities were measured along 4 traverses (lines), each with several probe spacings of course. Then we combined all those 4 data and treat them as one data by eliminating bad data. For example the shallow data associated with long lines are not a good representation for the area...
  12. rezaa

    Substation Grounding Design (Soil Resistivity model-3 layers)

    Fall-of-Potential(FOP) measurments should be compared to a simulated(using a software)FOP. For simulation of FOP we need to define a soil resistivity model. Usually 4 soil measurment traverses are used. 2 short traverses( representation for shallow layers soil model)within the station and two...
  13. rezaa

    Substation Grounding Design (Soil Resistivity model-3 layers)

    Is it ok to modify the soil layered structure model data(soil resistivity measurment model)to obtain agreement with Fall-of-Potential(FOP)measuements?
  14. rezaa

    Worse case soil model for grounding

    In general, the GPR of an extensive grounding system is influenced more by the deeper layer soil resistivity. For Simulation we can ignore the seasonal varation of the surface layer soil resistivity and consider the reresentatives of only deeper layers(using either summer/fall /winter/spring...
  15. rezaa

    Worse case soil model for grounding

    The top layer is wet from melted snow. We are assuming a 3-layer model. The worse case soil model is considered to occour in spring when the top crushed rock layer is wet from melted snow while the ground grid remains in frozen soil( surronded with higher soil resistivity). For the sake of the...

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