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  1. SidiropoulosM

    Shunt Capacitor & SVC

    You'll need to treat this as one project in two stages, done by the same vendor. The vendor should be able to give you a two stage design, with the view of minimizing the cost of stage 2 modification.
  2. SidiropoulosM

    Online temperature monitoring

    This is an interesting technology with many useful applications. There are two systems available now (1) the Valley Group and (2) EPRI. I have evaluated both and they both seem to be effective. Please write more details about your system.
  3. SidiropoulosM

    Wind Turbine Protection Help

    The protection system used will depend on what type of units you're using. Are they doubly fed induction generators? The manufacturer of the turbines should be able to give you the recommended protection scheme. As for the utility, they won't be concerned about impacts on the network, since...
  4. SidiropoulosM

    Electrical Transmission and Distribution Reference Book

    I bought the book from ABB recently for $250. It's money well spent.
  5. SidiropoulosM

    Zero sequence impedance of transformers

    Positive and negative sequence impedances are independent of whether the sequence currents are injected into the primary or secondary winding. The zero sequence impedance, however, will have very different values depending on what terminal we view. In this particular case, for zero sequence...
  6. SidiropoulosM

    electricty

    imok2, after a quick first reading of Beaty's article I think this man likes to play with words and semantic twists and ends up making some absurd statements. For example, he says: "Electricity is made of electrons, while electrical energy is electromagnetism and is made of photons&quot...
  7. SidiropoulosM

    electricty

    peebee, yes we ARE funny.....You know, I did my first year in physics before switching to engineering. The reason I switched is because my girlfriend at the time told me that engineers are more fun than physicists. I haven't regretted my switch one bit.
  8. SidiropoulosM

    electricty

    Suggestion to Jbartos: your argument that you can block energy with material layers doesn't mean anything. Energy is carried by material particles and surely can be blocked if you block the particles. This doesn't mean that energy itself is material.
  9. SidiropoulosM

    electricty

    Jbartos, don't be surprised that the statement "One just should not sleep during physics classes in the high school" has offended people. That is an offensive and intimidating statement. Now, the term "materialism" is foreign to physics and science in general. It was...
  10. SidiropoulosM

    Representative Load Profile!

    Correction to my post above: b, c, d = coefficients determined by the regression program
  11. SidiropoulosM

    electricty

    Something else to consider: all known forms of energy have their source in the sun. For example, the energy of falling water is a form of solar energy. The energy from wind is a form of transformed solar energy. Furthermore, the sun's energy is generated from a nuclear reaction, according to...
  12. SidiropoulosM

    electricty

    Jbartos, I don't know what high school you went to. In my high school, one of the best in Greece, Einstein's formula was mentioned. But none of us was expected to understand its implications. Even today, there are not many people in the world who fully understand Einstein's theories.
  13. SidiropoulosM

    Representative Load Profile!

    Assuming that you have sufficient historical data, you may group all days in two groups: (1) Weekdays (Monday-Friday) (2) Weekends (Saturdays, Sundays, holidays) You may then normalize the data for weather using the following regression equation: L=a+bx+cy+dz where, L =...
  14. SidiropoulosM

    electricty

    "Energy" is a much broader term than "electricity". There are many types of energy, one of which is electricity. Kinetic energy, for example, can exist without electricity. It can be transformed into electricity, however, under certain conditions. Therefore, energy and...
  15. SidiropoulosM

    dum question: v = Ldi/dt

    No, the inductor will not work like a short circuit in steady state AC. A short circuit has zero impedance. The inductor will have an impedance which will be a phasor quantity, i.e. will have a magnitude and a phase displacement. The phase displacement will be 90 deg. The magnitude will be...
  16. SidiropoulosM

    dum question: v = Ldi/dt

    On energization, the current builds up slowly. Remember, current through an inductor cannot change instantaneously. Mathematically, the current is the time integral of the applied voltage. Another way of saying this is that the inductor accumulates volt-seconds and the current increases in...
  17. SidiropoulosM

    115 kV Substation Switching Scheme

    The scheme you are proposing is a good one. There is a lower cost scheme, which is to provide one breaker only at the tap location, which will disconnect your generation from the 115 kv line. The disadvantage of this scheme is that your generation will be tripped for a fault on either section of...
  18. SidiropoulosM

    Load Shedding Scheme

    Direct load tripping as opposed to underfrequency load shedding may be the preferred solution here. You'll have a logic scheme which will trip pre-specified loads immediately when your generators trip. You can make this as simple or as complicated as you like. The scheme may be armed for certain...
  19. SidiropoulosM

    Line Loss vs. Transmission Voltage

    You will probably need two 3-phase cables for reliability purposes, rather than one cable. Another factor to consider will be the loading pattern of the cable and the resultant losses. The cost of losses will then determine the most economical voltage level and conductor size. This is not a...
  20. SidiropoulosM

    Is power cut explained in simple term possible?

    Bbird, you bring up many interesting issues but these have been discussed in the two "Big Blackout" threads I and II. There are many good comments, references and links in those threads on the subject of blackouts in general and the August 14 blackout in particular.

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