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Hndstudent
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Thread moved from the technical forums, so no Homework Help Template is shown.
The supply current was sampled 1024 times over a very short time interval. The data so obtained is given in column B of the accompanying Excel worksheet1. This worksheet has been set up to give a graph showing the spectral components of the data.
Question 3
where I1 is the r.m.s. value of the fundamental current, In the r.m.s value of the nth harmonic and n(max) is the number of the highest measurable or significant harmonic.
[Note the vertical axis of the spectrum graph is scaled in (current)2.]
iv) Attempt to synthesise the shape of the original waveform from its principal harmonics [e.g. sketch the waveforms of the harmonics on the same time axis and add them together].I am struggling with 3iii.
for I1 rms I have SQRT 15.8 + 8.77 + 6.25 = 5.55A
n max I have 15.8 as its the highest magnitude.
But I'm not sure what to do to find In?
any help would be appreciated.
Question 3
- i) Obtain the Fourier Transform for the data using the Fourier Analysis tool of Excel. The transformed data should commence in cell D2.
- ii) Identify the principal frequencies in the current waveform.
- iii) Estimate the total harmonic distortion [THD] present in the current waveform using the formula:
n max
THD(I)=1/I1 SQRT Σ (In)^2 x 100%
n=2
where I1 is the r.m.s. value of the fundamental current, In the r.m.s value of the nth harmonic and n(max) is the number of the highest measurable or significant harmonic.
[Note the vertical axis of the spectrum graph is scaled in (current)2.]
iv) Attempt to synthesise the shape of the original waveform from its principal harmonics [e.g. sketch the waveforms of the harmonics on the same time axis and add them together].I am struggling with 3iii.
for I1 rms I have SQRT 15.8 + 8.77 + 6.25 = 5.55A
n max I have 15.8 as its the highest magnitude.
But I'm not sure what to do to find In?
any help would be appreciated.