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Looking for lecture for plus null minus system [solved]

Discussion in 'Mathematics and Physics' started by Grossel, Feb 21, 2018.

  1. Grossel

    Grossel Active Member

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    Hi forum.

    I do not know the correct english term for the subject (maybe not the greatest way to start off a thread).

    I want to get a push in right direction where I can learn about theory about null/plus/minus (system ?) in 3 phase systems? Any teaching book/course you recommend?

    Thanks in advance
     
  2. JimB

    JimB Super Moderator Most Helpful Member

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    Sorry, but I have never heard that expression before.

    What does it do?

    JimB
     
  3. Grossel

    Grossel Active Member

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    I was afraid of that - it is fully possible that it cannot be directly translated into english. What I do know is that it is a way of simplifying a 3 phase system before or while doing calculations.
     
  4. dave miyares

    Dave New Member

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  5. JimB

    JimB Super Moderator Most Helpful Member

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    Sorry, that rings no bells with me.

    JimB
     
  6. alec_t

    alec_t Well-Known Member Most Helpful Member

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    I'm not sure what you mean either. Are you referring to a so-called 'modified sine wave', such as used in many inverter circuits and where the waveform is +V, 0, -V, 0, +V, 0, -V ..... ?
     
  7. Ian Rogers

    Ian Rogers User Extraordinaire Forum Supporter Most Helpful Member

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    Sounds like a reference to the 3 phase wave form... Phase 1 = 0v Phase 2 = +v and Phase 3 = -v.
    Watch youtube videos on Star and deta A/C machines..
     
  8. dave miyares

    Dave New Member

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  9. Grossel

    Grossel Active Member

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    Thanks for trying to help. If I do find an english terminology for this, I'll try to find this post and reply :cool:

    I also do know this - from years back at school: Student that doesn't study specific for electrical engineering (3 phase system / power grid theory) here won't normally touch this topic. I assume that is the same for most other countrys as well.
     
  10. dknguyen

    dknguyen Well-Known Member

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    Are you referring to "per-unit analysis"?
     
  11. Grossel

    Grossel Active Member

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    Thanks dknguyen, but it is not the per-unit analysis I'm looking for. That is btw pretty much the same in norwegian anyway.
     
  12. Grossel

    Grossel Active Member

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    My biggest problem here is that Google doesn't give any sensible returns when I do search for "null system" "plus system" "minus system". So I'm actually completely stuck as to be enable to provide enough info so that any one probably would know what I ask for. The poor results from Google searches indicates for me that the topic is named something fundamentally different in english.

    I do beleive (but have never learn in school) that "nul system" is when in a three phase system, one phase is considered as one phase system where neutral is threated as ground. That is a guess.
     
  13. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Is this what you're looking for?
     
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  14. dknguyen

    dknguyen Well-Known Member

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    Is that a seismology paper? haha
     
  15. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Yes, but perhaps the general analysis method could be used in other disciplines?
     
  16. Grossel

    Grossel Active Member

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    Thank you, but no - that paper is for oil/seismic only.
     
  17. Grossel

    Grossel Active Member

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    Eureka - At last I found what it is named on english: symmetrical components fault analysis - that it is :woot:
     
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  18. JimB

    JimB Super Moderator Most Helpful Member

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    Hmmm...

    Maybe I have led a sheltered life, but I have never heard of it.:(

    JimB
     
  19. dknguyen

    dknguyen Well-Known Member

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    That...doesn't sound like the translation at all lol.
     
  20. BobW

    BobW Active Member

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    In 3 phase system symmetrical component analysis, fault currents are separated into three components: positive sequence, zero sequence, and negative sequence. Those were the 3 terms Grossel was having trouble finding the translations for. The positive sequence current has the same phase rotation as the power system. The negative sequence currents have a phase rotation in the opposite direction, and the zero sequence have no phase rotation at all.
     

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