Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 59 replies
  • Subscribers 32 subscribers
  • Views 4988 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

High 3rd harmonic on the neutral

MS01
Afternoon,

I was wondering if anyone has nay experiences of having issues with high 3rd harmonic currents on the neutral on high-rised residential schemes? I appreciate  non-linear single phase loads will impact the 3rd harmonic and even on a balanced system harmonics are an issue but we are measuring it at 300% but I can’t think why this may be the case on a residential building.

Does anyone have any ideas?



M
Parents
  • 0
    AJJewsbury:
    A Megger MFT1741 will measure between 150 and 400 hertz, so if the harmonic current is high will it display 150 hertz rather than 50 hertz?

    Isn't it displaying the frequency of the voltage rather than the frequeny of the current though?

       - Andy.




    I  thought it was current, but I did an internet search before answering.



    What is frequency?



    Alternating current (ac) frequency is the number of cycles per second in an ac sine wave. Frequency is the rate at which current changes direction per second. It is measured in hertz (Hz), an international unit of measure where 1 hertz is equal to 1 cycle per second.

    https://www.fluke.com/en-gb/learn/best-practices/measurement-basics/electricity/what-is-frequency


    So what happens if there’s more than frequency in the same conductor, does the tester register the “dominant” frequency or a mish mash of them.


    Andy B.


Reply
  • 0
    AJJewsbury:
    A Megger MFT1741 will measure between 150 and 400 hertz, so if the harmonic current is high will it display 150 hertz rather than 50 hertz?

    Isn't it displaying the frequency of the voltage rather than the frequeny of the current though?

       - Andy.




    I  thought it was current, but I did an internet search before answering.



    What is frequency?



    Alternating current (ac) frequency is the number of cycles per second in an ac sine wave. Frequency is the rate at which current changes direction per second. It is measured in hertz (Hz), an international unit of measure where 1 hertz is equal to 1 cycle per second.

    https://www.fluke.com/en-gb/learn/best-practices/measurement-basics/electricity/what-is-frequency


    So what happens if there’s more than frequency in the same conductor, does the tester register the “dominant” frequency or a mish mash of them.


    Andy B.


Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines