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  1. juleselec

    Dynamic Stability Analysis Required?

    Very unlikely that transient (rotor angle) stability in the traditional sense of the term will be a problem for you, particularly if the GTGs are all identical and there are no synchronous motors in the system. Critical fault clearing times are most likely to be very high as identical GTGs will...
  2. juleselec

    Utility Impedance and Load Fkiw

    In most cases, there is no reason to include the Thevenin source impedance of a utility grid as long as the assumption holds that either 1) the grid is far larger relative to the connected consumer (or generator), i.e. short circuit ratio (SCR) is high, and/or 2) the utility has access to a...
  3. juleselec

    A coming engineering shortage ? ---- Who agrees ?

    I agree with ScottyUK. There does seem to be a shortage of engineers in the power industry, but only for certain cohorts. This is from the 2015 Center for Energy Workforce Development report on gaps in the energy workforce pipeline: While it is not just for engineers, I'd assume the age...
  4. juleselec

    Current Limiting Fuse Instantaneous Peak vs Panel SCCR symmetrical RMS

    It's probably worth going back to the definitions / intentions of the different SCCR terms. Usually, symmetrical rms SCCR refers to a thermal rating (heat energy i2t), which is often why there is an associated rated time, e.g. 25kA for 1s, or it is converted to an MVA rating. The rough idea is...
  5. juleselec

    Cable Ampacity - IEC for multiple layers

    All of the current ratings and derating factors in IEC 60364-5-52 are calculated based on IEC 60287 (which in itself is based on the Neher-McGrath equations) for the most common cable types and installation conditions found in IEC countries (mainly Europe). Now if you've got weird...
  6. juleselec

    Minimum Fault Current

    From an overcurrent protection coordination standpoint, the minimum fault is the smallest fault current that represents a "real" short circuit for that system. Normally, something like 80%-90% of the minimum fault current is used to set a fast definite time or instantaneous element, i.e. you...
  7. juleselec

    Would you take a 20% pay cut to learn a specific software?

    In my experience with many different software packages (in the power systems world), the easy part is learning how to drive the software, e.g. press the buttons and navigate the user interface. The hard bit is understanding the algorithms / calculation engine behind the UI, developing the...
  8. juleselec

    Solar Farm - PQ/Grid Compliance Requirements

    Have a look at the ENTSOE grid code (https://www.entsoe.eu/major-projects/network-code-development/requirements-for-generators/Pages/default.aspx), particularly Chapter 3 on the requirements for Power Park Modules (i.e. non-synchronous generation like solar PV plants). This is fairly...
  9. juleselec

    IEEE Test Bus Systems Query & book recommendations

    The IEEE test systems are essentially publicly available solved cases, which may or may not have been built based on actual networks. From my experience, they tend to serve two purposes: 1) benchmarking of software algorithms, and 2) academic research. For 1), this can apply to both commercial...
  10. juleselec

    Subtransmission voltage regulation

    I work at a transmission utility and we have on-load tap changers on transformers at both transmission to sub-transmission (e.g. 330/132kV) and sub-transmission to distribution (e.g. 132/33kV) levels. There are also switched shunts and (very occasionally) SVCs for regulating sub-transmission...
  11. juleselec

    Installation of series Capacitor Bank in Transmission Lines.

    As others have pointed out, series caps are used primarily to expand a line's real power transfer capability (i.e. increase surge impedance loading) and can also improve transient stability. In principle, series compensation could improve voltages at the receiving end since the line itself...
  12. juleselec

    Transient Stability

    All of these plots have their uses and you should look at them to interpret what is happening during the simulation. Examples: - When a system loses synchronism or is poorly damped, this will often be reflected in oscillations in the real / reactive power outputs. - The exciter current and...
  13. juleselec

    New utility engineer; looking for a good overview of distribution

    The book by Bayliss and Hardy is very practical and useful for someone starting out: http://www.amazon.com/Transmission-Distribution-Electrical-Engineering-Edition/dp/0080969127
  14. juleselec

    Transient Stability

    What you are referring to is the steady-state stability of the system, and this is more or less related to the loading of the generator(s). Check out page 5 of http://www.cigre.org.br/archives/pptCigre/05_Transient_Angle.ppt. This shows the simplest case of a generator connected to an infinite...
  15. juleselec

    Fault analysis in an industrial network - software?

    PSS/e is overkill for this kind of work, and it's pretty expensive too. If you're on a budget, SKM Power*Tools for Windows is probably your best bet. ETAP has been trying to position itself as the de facto standard for industrial networks, but it's a little more expensive. Other suitable...
  16. juleselec

    Power System Analysis for Overload?

    From the sounds of it, you have a secondary selective system so the worst case loading conditions come about when you operate with one branch element (e.g. line/cable, transformer, etc) out of service and the bus-tie closed. This configuration is sometimes called an n-1 contingency scenario. So...
  17. juleselec

    Do nearby lines affect the impedance of a transmission line?

    The appropriate approximation for Carson's equations will depend on your application. For short lines, it is common to use an approximation that simply neglects the series expansion terms (P and Q). Apparently there is around a 3% error when you do this (can't find the reference for that...
  18. juleselec

    Wiring to AS/NZ 3000-2007 in the USA for export

    I'm with FreddyNurk and Boof on this - the wiring was most probably not rejected because of AS3000, but as a result of a hazardous area inspection, i.e. compliance to AS60079 or AS2381. In Australia, the use of conduits between junction boxes is definitely NOT preferred, nor is it particularly...
  19. juleselec

    Transformer at no load

    This is something that's a bit misleading in the software. The magnetizing current is the current that is calculated using the polynomial saturation characteristic based on the magnetizing flux. This is used to determine the magnetizing reactance, which is then used to calculate the phase...
  20. juleselec

    Gas group as per IP 15 hazardous area classification

    It'll most likely depend on the concentration of H2S, which is a IIB T3 material and probably more onerous than the long chain hydrocarbons in your gas mixture (e.g. C7+, C9+, etc). If you are talking trace elements, then it's probably not worth taking it into account.

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