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  1. O

    Ampere's law to calculate the B field from a balanced three-phase system

    Thanks again. I played around a little, and tried to calculate the magnitude of the resultant \vec{B} at point P and got the figure below. What do you guys think, looks reasonable? I might have done some errors, I did this in a rush. The interesting point is that the magnitude of B is zero some...
  2. O

    Ampere's law to calculate the B field from a balanced three-phase system

    Thanks, both of you, I really appreciate the help. Things are much clearer now.
  3. O

    Ampere's law to calculate the B field from a balanced three-phase system

    By the way, lets say I never saw that table stating that the value of B is different from zero at point P. So without knowing about thetable, I would apply Ampere's law as shown in the picture from post #1, and concluded that the value of B to be zero for every point in space that lies on the...
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    Ampere's law to calculate the B field from a balanced three-phase system

    Thanks Jim, and after reading the pdf you linked in post #6, it became clear. First we consider one conductor and calculate the value of B at point P, then we consider the other two conductors individually and add the values of B from the three conductors to get the value of B at point P.
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    Ampere's law to calculate the B field from a balanced three-phase system

    I will have a look at the pdf from the UK utility company later when I am home. The table is in a compendium written in Norwegian by a professor at the Norwegian university of science and technology, and his source is the Norwegian radiation protection authority, this one is also in Norwegian...
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    Ampere's law to calculate the B field from a balanced three-phase system

    Thanks for the replies. I looked at a table which showed typical values of B at a distance x from a 420 kV transmission line, and they were not zero. So if I would want to calculate the value of B below the transmission line at ground level, I would have to use Biot-Savart equation on each...
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    Ampere's law to calculate the B field from a balanced three-phase system

    I am a little confused when I try to use Ampere's law to calculate the B field from a balanced three-phase system. Consider the following, shown in the picture below: Lets say I want to calculate the value of B at a distance r (radius of my Amperian loop), the value of r is big enough so that...
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    Phase Locked Loop

    Thank you @jim hardy , i'll read what you suggested tomorrow morning.
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    Phase Locked Loop

    I have some trouble fully understanding the PLL block diagram shown below in the figure. The PLL circuit is used to generate currents (i alpha and i beta) which are in phase with the positive fundamental sequence of the voltage. I am using the book "Instantaneous Power Theory and Applications...
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    Positive Sequence Detector

    Hi, I am studying a positive sequence detector and have some trouble understanding it. I understand most of it, but the author in the book "Instantaneous Power Theory and Applications to Power Conditioning" writes: For extracting the fundamental positive-sequence voltage with the dual method...
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    Harmonic sources, flowing from load, why?

    Thanks for the explainations @anorlunda and @Windadct , but I am still abit confused when a passive shunt filter is connected in parallel, see figure. So if a nonlinear load causes flow of fundamental + harmonics, but the filter is implemented in such a way that the source only has to supply...
  12. O

    Harmonic sources, flowing from load, why?

    I have been thinking of this and can not seem to understand why nonlinear loads can be tought of harmonic current sources injecting current back into the grid? For example if you connect a passive filter in parallel to attenuate the 5th harmonic, the 5th harmonic would flow between the filter...
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    Boost converter in Simulink problem

    Aha, thank you.
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    Boost converter in Simulink problem

    Hi I am trying to simulate a boost converter in Simulink, but I have a problem. When I measure the inductor current it shows as a triangular waveform instead of an exponential waveform like I would expect, does anyone know why? Does simulink do some simplification I am not aware of...
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    Help me understand transformer vector groups

    Very nice explanation, thanks, both of you.
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    Help me understand transformer vector groups

    Hi, I have problems understanding why, for example, a Yd1 connection introduces a -30 degree phase shift, see image below. How should I think when I want to produce vector groups like that, and derive myself what the phase shift should be? Thanks..
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    Virtual Intertia in Power Systems

    Hi again PF. I recently came across the term "virtual inertia" when reading about photovoltaics and power converters (DC/DC, DC/AC etc.). Article: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6953370, not sure if people are able to view the article, I have access via university library...
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    Odd Harmonics in Power System - reduction

    @jim hardy , excellent graphical approach - as always.
  19. O

    Odd Harmonics in Power System - reduction

    Thank you all. I hope that some time in the future I will be as knowledgeable within power system as you guys.
  20. O

    Odd Harmonics in Power System - reduction

    So shunt capacitors actually gives two benefits in a power system. Harmonic reduction and reactive power compensation, i.e. helping such that voltage stays within specified limits. Are shunt capacitor designed to do both tasks at the same time, or do you have to design them individually?
  21. O

    Odd Harmonics in Power System - reduction

    Hi, could anyone explain to me how odd harmonics in the power system are reduced or removed? I've read that in transformers the harmonics produced by the load circulate if the secondary side is wired as delta configuration, yet star is usually used on secondary side i believe? I've looked...
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    Salient and Non-Salient pole Synchronous Generator

    Yep, your answer was helpful, thank you!
  23. O

    Salient and Non-Salient pole Synchronous Generator

    I found the equation mentioned above, referred to as "Eq. (5.69)" in the text below. It's derived from the same phasor diagram shown in the PDF document you linked in figure 4-41, just note that r_a is assumed to be negligible.
  24. O

    Salient and Non-Salient pole Synchronous Generator

    I doubt that I know more, perhaps I've mistaken something, because I can only find information on this working on salient pole motors, if one google the term "reluctance power". However, I would like someone with experience with this kind of topic, so we can avoid any confusion. I was looking...
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    Salient and Non-Salient pole Synchronous Generator

    Actually, this got me wondering; why are salient pole generators preferred over non-salient pole generators? Ok, fine that centrifugal forces at high rpm are to much for salient pole rotors, so non-salient rotors are used instead. But you say, that salient pole generators would be preferred in...
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    Salient and Non-Salient pole Synchronous Generator

    Thank you for the answer.
  27. O

    Salient and Non-Salient pole Synchronous Generator

    Hi, I was wondering if some kind soul could explain to me why salient pole machines are preffered in hydropower? From what I've read salient pole machines are preffered for applications with "low" rpm, while non-salient poles are used for applications that runs at higher rpm. O What is the...
  28. O

    Voltage and Reactive Power Relationship

    Ok, thank you, I think I finally got to understand my initial question a whole lot more, I really appriciate your help.
  29. O

    Voltage and Reactive Power Relationship

    Quote from one the posts you linked in your first post: Why must the terminal volts and total MMF have the same radius? I understand that terminal volt should be of a constant value if connected directly to infinite bus, but I do not fully understand why the total MMF should be of the same...
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