# Search results

1. ### 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. ### 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. ### 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...
4. ### 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.
5. ### 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...
6. ### 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...
7. ### 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...
8. ### Suggestions for a Power System Analysis book?

Thanks all. I ordered used copies of the books suggested by jim hardy and Dr.D. I dont expect good conditions, but they were so cheap so I'll wait and see. If I like them I can buy them in better condition later. The book suggested by Electrical also seems like a good choice, I will take a...
9. ### Suggestions for a Power System Analysis book?

Hi, I want a book about power system analysis that I can have laying around and read from time to time. I have taken a course in power system analysis some time ago, where I was taught simple fault analysis including unbalanced faults, frequency and voltage control. So to maintain this...
10. ### Phase Locked Loop

Thank you @jim hardy , i'll read what you suggested tomorrow morning.
11. ### 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...

Bump.
13. ### 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...
14. ### 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...
15. ### 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...
16. ### Boost converter in Simulink problem

Aha, thank you.
17. ### 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...
18. ### Help me understand transformer vector groups

Very nice explanation, thanks, both of you.
19. ### 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..
20. ### 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...
21. ### Odd Harmonics in Power System - reduction

@jim hardy , excellent graphical approach - as always.
22. ### 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.
23. ### 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?
24. ### 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...
25. ### Engineering Power Quality with focus on harmonics

Hi Anyone got any suggestions/recommendations for literature either available for free online or books that I have to buy? My background: Electrical engineering student, working on a project that is about analysis of power quality with focus on harmonics.
26. ### Pelton Turbine - Cavitation

Thank you for your answer. My reference was a PDF document a Norwegian power company published during the celebration of a 100 year old power station. They just said during the life time of the power plant they've had problems with cavitation of one of the pelton turbines, and did not talk...
27. ### Pelton Turbine - Cavitation

Hi, I have a question; can cavitation occur in Pelton turbines? From my understanding we have atmospheric pressure inside the turbine at the runner wheel, so that means cavitation will not occur? However I read somewhere that there was some problems with cavitation in a Pelton turbine, so that...