Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. powerpi

    Transformer Neutral CT sizing for REF protection

    Hello Nikola This depends of the type of the network. The Siemens CT requirements are presupposing a symetrical ISCC fault current with some margin. This is the case if you have a strong network with little to no DC component. If you use an iron core CT's as a rule of thumb, the answer is No...
  2. powerpi

    Faster clearing Time 69 kV Substation Grounding

    Hello Is your network grounded directly? Perhaps isolated? Do you have any experience of remote end Z2 tripping in case of high infeeds from other lines in case of S/S nearby faults? Regards
  3. powerpi

    Matlab coding help

    Yes, now I have added additional delay to the "j" index and it works fine. Thank you very much for your help. I wouldn't have make it without you. In general the negative an positive values of integral should compensate each other out, but when unevenly distributed zero crossings are present...
  4. powerpi

    Matlab coding help

    I have added two lines for finding the zero crossing in the original signal "y". The "zx" returns an index of the points where zero crossing takes place. Perhaps this information can be used to further extend the delay of "integral" until this index is reached. Now, the "integral" function, as...
  5. powerpi

    Matlab coding help

    a, ok, now I see. I have tested it with the normal sine function and it works ok. now I only need to restart the integral with some delay, after the next zero crossing. Otherwise thanks. Much appreciated.
  6. powerpi

    Matlab coding help

    Hello again Thanks for the code. I have run it and I have found two issues. First, I need to numericaly integrate the signal ("y" in your code, "is" in mine). So I would need to use one of the integral functions available. I thought of trapz, but I would have to tell it when to stop and when...
  7. powerpi

    EHV busbar protection slope

    Hello I have a recurring question about the settings of a low impdance busbar Protection systems. We are using mainly Siemens and ABB products and leaving the default slope (k) settings of e.g. 80 % (k=0.8). However, it constantly puzzles me on how to calculate the proper slope regarding the...
  8. powerpi

    Matlab coding help

    I am not sure if I understand you correct. I have added a piece of code in my reply so you can se what I am doing. First part is of no importance as it is only the definition of constants, to be used later in the code. After the "for" loop it is when it all starts. I have calculated the primary...
  9. powerpi

    Matlab coding help

    Hello I am running a Matlab script and I would need a tip (or help) in coding on how to get things done. I am trying to simulate the CT saturation in a protection core CT. To do this I need to integrate the area of the secondary current (lower side of the plot) and compare it to a predefined...

Part and Inventory Search

Back
Top