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  1. oldfieldguy

    Hoover Dam Explosion

    Looks like a transformer let go. Link old field guy
  2. oldfieldguy

    Engine RPM for continuous duty generator

    I used to 'know' that one did not use an 1800 RPM (or higher) engine for continuous duty generation. I have an offshore facility that now has TWO dead 750 kw natural gas fueled generators. Both are forty years old 'big iron' 750 RPM units rated at 750 KW for when this was a major compressor...
  3. oldfieldguy

    Was sitting in on a conference call

    Was sitting in on a conference call today and one of the participants said that the recent installation of a high resistance grounding system resulted in an increase in arc-flash hazard. I've installed and worked around dozens of HRG systems in 480-volt systems and have done a few analyses of...
  4. oldfieldguy

    Another system that was a marvel of its time

    https://blog.metrolinx.com/2019/11/13/time-in-a-box-union-station-prepares-to-retire-a-vast-interlocking-system-thats-guided-every-train-in-and-out-of-toronto-for-almost-90-years/ old field guy
  5. oldfieldguy

    Plant explosion

    Close to home - this is in southeast Texas. I've worked there: https://kfdm.com/news/local/breaking-plant-explosion-in-jefferson-county-rocks-homes-for-miles old field guy
  6. oldfieldguy

    Arc-flash labels in outdoor switchyards

    Just about the time that I relax about arc-flash labelling, somebody pops up another question. I have a facility that has an outdoor switchyard - 115 kV in, a couple of nice transformers that drop it to 4160, a few outdoor vacuum circuit breakers (5 kV) to feed underground cables to the...
  7. oldfieldguy

    SF6 gas testing

    Assuming a modern outdoor SF6 circuit breaker, what's the thought on routine testing of the gas? Breaker has been installed and in normal service for a varying number of years, has had no leaks, never been opened to the atmosphere, has not interrupted faults near its rated capacity. I...
  8. oldfieldguy

    NEC Classification vs. Mil-SPec

    Our measurement group (natural gas pipeline) is looking at purchasing a videoscope (borescope) for use in inspecting the internals of various parts of their equipment. Their candidate is shown to be "MIL-STD-810G, METHOD 511.6, Procedure I (operation in an explosive atmosphere test)". I'm the...
  9. oldfieldguy

    Life expectancy of microprocessor-based protective relays (IED)

    The question has arisen at my workplace as to what we expect out of these things. I have devices installed in excess of twenty years ago. What do I tell our managers about their life expectancy? We're starting to see sporadic failures on devices. That is not to mention that software...
  10. oldfieldguy

    Wstinghouse HU Xfmr Diff Relay

    I guess I've been out of the field too long. does anybody remember the Westinghouse IL for their HU relay? old field guy
  11. oldfieldguy

    Stray flux overheating transformer case?

    Anybody want to comment? A little history. Original transformer was installed in 2006. It failed catastrophically in 2010. The manufacturer said the cause was an external fire, although I pointed out this discoloration on that transformer's case, away from the obvious fire damage. We...
  12. oldfieldguy

    What's wrong with this picture?

    I have a s****ns CGP 9000 HP 1800 RPM 4160-volt motor in service driving a centrifugal natural gas compressor through a step-up gearbox. The motor is fed by a s****ns VFD. Last year the motor was taken off-line due to high vibration. Investigation revealed that the cooling fan, internally...
  13. oldfieldguy

    Other conduit sealing compounds?

    I was posed the question by a manager this morning as to whether there were other, not water-activated, sealing compounds that could be used in the place of 'chico' water-mixed compound in sealing fittings for use in classified areas. I seem to remember some discussion of these some years ago...
  14. oldfieldguy

    Common practice for 13.8 kV grounding

    I am fighting a proposal by our 'management' to require the utility company to provide us with an ungrounded 13.8 kV supply for a couple of large motors and station auxiliaries. I work on the US Gulf Coast. I have NEVER seen one of my former clients use an ungrounded 13.8 system. The common...
  15. oldfieldguy

    Dual trip coils

    I have a bit of experience in the southern US with industrial and utility power systems, but of late I have had a recurring conversation concerning the employment of dual trip coils on 5-15 kV circuit breakers in industrial environments. My experience is that they are relatively rare in heavy...
  16. oldfieldguy

    Help a guy with pictures!

    I'm putting together a presentation for introducing some of our station personnel to the wonderful world of medium voltage switchgear. Naturally, pictures of their new switchgear are easy. All I have to do is walk in the building and take what I want. However, I want to show some slides of...
  17. oldfieldguy

    What would you teach?

    I've been in electrical power since 1977, 480-500,000 volts. I've designed, commissioned, maintained, etc. Hands-on and as supervisor and manager. for the past three years I've worked for an interstate natural gas pipeline where 480 volts was "high voltage" and 1000 kVA was a "big...
  18. oldfieldguy

    Surge protection on thermocouple inputs

    Didn't find anything definitive in a search here, and I Googled the web, too. One of my minor stations took a pretty good lightning hit during a recent storm and blew a bunch of I/O cards, all RTD and thermocouple inputs. Not really in my purview as a power guy, but is there a particular...
  19. oldfieldguy

    Conduit drains?

    As is often the case, we had a little problem and I got asked a question. We had a low voltage circuit catch fire and burn at one of my sites. The wiring in question was in conduit, installed in a Class I Div. I area and was contained except for some smoke which unfortunately triggered smoke...
  20. oldfieldguy

    S****** GM-150 VFD

    We have three, two 9000 horsepower, one 7000 horsepower. the 7000 went in service three years ago. It has had two failures, each requiring three weeks outage between bringing in the expertise to diagnose and then to get parts to repair major damage to bus. One of my 9000 horsepower units is...

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