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  • Users: Bung
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  1. Bung

    transformers vector group selection

    A rose by any other name would smell as sweet... A-phase is 120deg from B-phase. 1 o'clock is 120deg from 5 o'clock. So Rename A-phase on a Yd1 to B-phase and voila! Yd5. So there is no fundamental physical difference, and hence no oneed to manufacture anything otherthan Yd1 or Yd11. A simple...
  2. Bung

    Transient Fault 132 kv single circut

    Do you have any more information: -phase fault or ground fault? or a mixture? -any fog, salt fog, recent high winds? -is protection duplicated? If so, do both operate? are the VT circuits ok? has this just started tohappen, or is it an on-going problem? if it is recent, does it coincide with...
  3. Bung

    B&S OQFRN fuse characteristics

    Does anyboody have the characteristics of the old B&S 12OQFRN fuses? I am particularly interested in getting the TCCs and the minimum breaking current figures as given on test certificates. Apparently the minimum breaking currents are NOT the same as the data published in the catalogues in the...
  4. Bung

    matrix arguments

    Yes, you can use any variable to get data into (and out of) a Mathcad program function. The only downside is that Mathcad doesn't like mixed units in an array or matrix. All variables outside the "program" are available inside the protgram; but variables inside the program are local to the...
  5. Bung

    Nuisance Earth fault trip

    You could have a faulty surge arrester (lightning arrester) on the feeder that was tripped in error. If it is the case, it will be on one of the phases that was not faulted on the correctly tripped feeder. I've seen this happen when a 5kV arrester was used (in error) on a feeder - it managed...
  6. Bung

    3 Phase Trip

    What about a very high zero sequence infeed to a ground fault from a remote ground point (tranfarmer star point, etc) with no active source behind it? Bung Life is non-linear...
  7. Bung

    Mathcad version 12 , ugly comment !!

    I like it. It has helped my debugging at least once - I didn't get the squiggly green line when I was expecting it, so I knew the varaible I was trying redeine hadn't been. Bung Life is non-linear...
  8. Bung

    Mathcad 13 using Mathconnex

    Mathconnex seems to have disappeared with Mathcad 12/13 - much to my irritation, as I had a few Mathconnex projects from earlier versions that were quite useful. But you can use Excel to "talk" with Mathcad (via an add-in, or just as a "normal" Windows thing (ODE or whatever the current...
  9. Bung

    Mathcad 13 - Opinions Please

    I like the look of the new version of Maple - Maple 10. Just finished a 30-day trial. The interface is now quite similar to Mathcad, and it seems to have a few nice things in addition to make it more useable - and I didn't think that would be too easy, given the ease of use of Mathcad. BUT...
  10. Bung

    Distribution analysis

    re Unix downsides- unix (Linux, HP-UX, etc) might be technically great, but you still have to deal with the non-unix world, and anybody who pretends that all unix apps support X-windows equally well is kidding themselves just as much as those who think all windows apps are truly windows...
  11. Bung

    selecting a dream motor

    series wound dc motor is pretty much unbeatable for starting torque and ease of speed control (hence their popularity as traction drives). Bung Life is non-linear...
  12. Bung

    single busbar or double busbar

    Vikkyarora, if other utilities are anything like mine, you won't be given the option of which you want to sell. It will all be tied up tight in the specification, and they will decide what they want to buy. I haven't come across a utility yet that lets an equipment supplier have the final say...
  13. Bung

    High Z vs Low Z diff protection?

    The high and low refers to the burden of the relay. High impedance protection is voltae based - it uses the voltage output of the CT, so usually requires CTs with a known knee-point voltage that is high enough to meet certain criteria. Low impedance lust uses the current output directly, so...
  14. Bung

    Distribution analysis

    For distribution level, DINIS from Kainos has some good points - the major downside it runs on Unix boxes. Also Siemens seem to have taken on the old PTI suite of PSS/U, Viper or whatever it is called now. Digsilent, ERACS are more transmission level products, and Dapper strikes me as being...
  15. Bung

    Transformer cooler controls

    Thanks electricpete - every litle bit helps. I did find a bit in the old Westinghouse book in the chapter on transformers, but it still requires a knowledge of more about the transformers than I already have. And if we are going to guesstimate, I would like to at least know the size of the...
  16. Bung

    Transformer cooler controls

    We have a bit of a debate going at the moment about the temperature "gradient" between oil temp indicator settings (OTI) and winding temp indicator settings (WTI) on power transformers using oil pockets and load current driven heaters to emulate the winding temperature. We have a number of...
  17. Bung

    Inductive Proximty Switches Sensing Aluminum?

    me again - aluminium isn't diamagnetic, it is paramagnetic. Shows you shouldn't rely on memories of high school physics over 1/3 of a centruy after the event! Bung Life is non-linear...
  18. Bung

    Inductive Proximty Switches Sensing Aluminum?

    Actually, thinking about it a bit more, wouldn't the fact that aluminium is diamagnetic have some bearing on what is happening here? Bung Life is non-linear...
  19. Bung

    Inductive Proximty Switches Sensing Aluminum?

    Wow, sounds cool. My son has a stack of old HDD magnets kicking around somewhere - can't wait to get home to try it! But he didn't have any trouble extracting them, as far as I remember. Must be a different make. Bung Life is non-linear...
  20. Bung

    Demand Factor Dilemma

    I don't think that any IEC compliant solution would also be NEC compliant. Or that this kind of thing is addressed at all in any IEC standards. Bung Life is non-linear...

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