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Recent content by kraigb

  1. kraigb

    facts about xlpe cable

    You might have noticed some differences of opinion, in these responses, which is to be expected. These days, both EPR and TRXLPE can be very good insulation compounds. The trick is in finding a good manufacturer, and making sure that they know you care about the quality of the cable they make...
  2. kraigb

    Fused Elbows

    Good point, edjh2. Those meters really do work pretty well. We have been able to make use of the low impedance meter in some situations where the high impedance meters we normally use won't work. There have been a few rare instances where the test points didn't work and we were unable to...
  3. kraigb

    Cable insulation

    In response to the question from Michael Sidiropoulos: You are correct that the losses go up as the voltage goes up, but what you consider to be negligable depends more on the economic philosophies of the company owning the lines. Depending on the ROI (return on investment) horizon a company...
  4. kraigb

    Fused Elbows

    I have use these at two utilities... The newer fused elbows have fewer problems associated with the EPR materials from which they were made than did those manufactured 10 or 15 years ago. The older materials didn't seem to allow you to separate the two halves of the elbow / fuse housing...
  5. kraigb

    Cable insulation

    Scottf: Sorry about the late reponse on this. I haven't been checking the forums as often as I used to... The relation between capacitance and insulation does seem counterintuitive at first, but I think I can explain it in language that is more or less English. Capacitance changes with...
  6. kraigb

    testing distribution cables

    All of the above posts are entirely correct that sufficient grounding practices are the best method to handle this behavior in the insulation. There is actually a diagnostic technique that depends on the return voltage that you have described. The return voltage technique is based on...
  7. kraigb

    Cable insulation

    Depending on the operating voltage, there is one other economic factor to consider. Capacitive losses can make a difference at higher voltages and higher enrgy costs. The thinner the insulation wall, the greater the capacitive losses of the cable will be. For transmission voltages, the...
  8. kraigb

    Over Head Transmission Line

    Alcoa, the developer of the SAG10 software package, has some whitepapers on their website at the following URL: http://www.sag10.com/download.htm Although a lot of the files they have on this page are for peolpe who already have SAG10, there seems to be some decent information in the following...
  9. kraigb

    Substation Warning Signs

    Thanks, dpc. I see that ANSI has a number of point documents under Z535 Z535.1-1998 on Color Codes Z535.2-1998 on Safety Signs Z535.3-1998 on Safety Symbols Z535.4-1998 on Product Safety Labels and Signs Has anyone needed more than just Z535.4 to stay in compliance and to exercise...
  10. kraigb

    Substation Warning Signs

    What is the latest standard used for definition of the placement, content, symbols, etc. for substation warning signs in the United States?
  11. kraigb

    Overhead Conductor Ampacities

    Most of the line designs I have seen base the ampacity on a guess as to what the worst case ambient air temperature would be for the area in which the line will be installed. 90-95 degF (32-35 degC) is a little unusual, but not outside the summertime operating temps we might expect to see. I...
  12. kraigb

    cables

    I agree with what WBD says regarding the effect load as a prophylaxis against moisture, so I will not repeat any of that. I think your last question is a request for the expected life of a cable? There are a few dependent factors when you are trying to determine life expectancy, and it is...
  13. kraigb

    Significant digits and complex numbers

    Well, I have taken some time to mess with this some more, and the least painful method is the text conversion method that Greg Locock proposed. As Greg mentioned, though, the actual caculations need to happen in some other hidden cells, but this does provide a formatted output that is a little...
  14. kraigb

    Significant digits and complex numbers

    Thanks, everyone. Yes, as GregLocock surmised, it is Excel that I am using. Sorry about my omission. For Prex: You are correct. The complex number functions are included in the Analysis Toolpak Add-in. I just tried the custom formatting, and Excel seems to ignore that. I will give these...
  15. kraigb

    Significant digits and complex numbers

    I am running into some difficulty formatting the numbers that come out of manipulation of complex numbers. In order to do the mathematical computations, I have to break a complex number down to do operations on the imaginary and real components separately. When I return to complex notation...
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