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Recent content by gigahertz

  1. gigahertz

    % Total Harmonic Distortion

    % current THD can be very misleading. It is percent of the fundamental current. If the fundamental current is 100 amps on a wire rated for 100 amps, 126% THD is bad. If the fundamental current is 1 amp on the same wire, 126% THD is completely negligible. Generally, current will almost always...
  2. gigahertz

    Big blackout. What happened?

    This type of thing happens because the system is at some point constructed for n-2 or n-1 conditions, and then consumption growth causes peak loading which exceeds the limits for n-1 operation (ie, less than n, no operation). The growth is allowed to occur faster than additional necessary...
  3. gigahertz

    Electrical safety issue

    The only way that is acceptable as a locking mechanism under any code is if the external lock also prevents opening the door to get to the breaker. Check under definition of lockout in any code ...
  4. gigahertz

    rs232 through slip rings?

    If you can convert your data to fiber, there are several styles of fiber optic rotary joints available that may meet your needs.
  5. gigahertz

    Fuse rating on lockout relay circuit

    Electricpete: I'll bet you also have DC motors on oil pumps with no overload/overcurrent protection ...
  6. gigahertz

    Fuse rating on lockout relay circuit

    If you're looking at NEC issues, 240-3(a) specifically requires NOT installing overcurrent protection where an open circuit will create a hazard and I have always seen this rule applied for protection circuits of large generators. The circuit requires short circuit protection only, which is...
  7. gigahertz

    Can 50Hz be run at 60Hz?

    Why not just run the generator at 50 HZ (slower speed)?
  8. gigahertz

    GIS SUBSTATION PHOTO

    http://www.abb.com/global/abbzh/abbzh251.nsf!OpenDatabase&db=/global/seapr/seapr035.nsf&v=6312A&e=us&c=E7EF0335F231D88285256AB900400274
  9. gigahertz

    Wiring Method per NEC

    No code requirements for separation so long as insulation of terminals and conductors are both greater than the higher voltage.
  10. gigahertz

    Meggering of LV Busbar

    Not necessary. You get a lot more from IR inspection while it is energized. Then you know where to work when you are down.
  11. gigahertz

    Meggering Test Voltage

    For medium/high voltage cables (>600V), you should contact the cable manufacturer for their recommended test voltage, which is usually done for acceptance testing after installation of the cable. This then gives a comparison to the factory testing results to look for damage. Once installed and...
  12. gigahertz

    need motor for small wind tunnel, 0-10,000rpm, 12A, 4-8" dia,

    Look here> http://www.amc-inc.com/vsrmotors.html
  13. gigahertz

    HI GUYS I HAVE JUST RUN INTO AN UN

    Radiation from Comms, Radar, etc?
  14. gigahertz

    Standard IEC TESTS FOR A GENERATOR

    IEEE Standards are International: IEEE Guide: Test Procedures for Synchronous Machines Part I-Acceptance and Performance Testing Part II-Test Procedures and Parameter Determination for Dynamic Analysis IEEE 1995;Softcover;1995;ISBN 1-5593-7710-0; Product No.: SH94401-TBR; IEEE Standard No...

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