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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
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  • 0
    Back during the Covid lockdown I decided I didn’t need to buy anymore tools, particularly when I wasn’t working.


    However I made the mistake of just having a look through EBay and bought a bargain brand new Megger DCM305E leakage clamp meter. I have only used it half a dozen times and still haven’t used all the buttons, bearing in mind there’s only three buttons the one I have not used is a low pass filter taking the frequency range down to 50-60 Hz.


    From the Megger literature, which is a bit scant:


    Additionally, this clampmeter vastly improves measurements on circuits with harmonics/electric noise on the cables using a low pass filter of 50/60 Hz.


    The cut-off frequency of the low pass filter is about 100 Hz with an attenuation characteristic of approximately -24 dB / octave.


    I presume I could make use of that feature in an installation like this.

    Megger DCM305E


    Andy B.
Reply
  • 0
    Back during the Covid lockdown I decided I didn’t need to buy anymore tools, particularly when I wasn’t working.


    However I made the mistake of just having a look through EBay and bought a bargain brand new Megger DCM305E leakage clamp meter. I have only used it half a dozen times and still haven’t used all the buttons, bearing in mind there’s only three buttons the one I have not used is a low pass filter taking the frequency range down to 50-60 Hz.


    From the Megger literature, which is a bit scant:


    Additionally, this clampmeter vastly improves measurements on circuits with harmonics/electric noise on the cables using a low pass filter of 50/60 Hz.


    The cut-off frequency of the low pass filter is about 100 Hz with an attenuation characteristic of approximately -24 dB / octave.


    I presume I could make use of that feature in an installation like this.

    Megger DCM305E


    Andy B.
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