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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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    I remember someone who was better at maths than I explaining that the worst case is a neutral 3rd harmonic twice the phase current.

    And this happens when computer power supplies are being run at about 60% of full load - which, of course, is what most of them do run at.

    However I would be a bit suspicious of any meter which is designed for use on 50Hz giving an accurate reading at 150Hz. I'm sure some do, but maybe not all and I would not expect this in a block of flats, a data centre yes.
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  • 0
    I remember someone who was better at maths than I explaining that the worst case is a neutral 3rd harmonic twice the phase current.

    And this happens when computer power supplies are being run at about 60% of full load - which, of course, is what most of them do run at.

    However I would be a bit suspicious of any meter which is designed for use on 50Hz giving an accurate reading at 150Hz. I'm sure some do, but maybe not all and I would not expect this in a block of flats, a data centre yes.
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