Hioki 3196 - Page 214

12.4 Formulae
208
Total harmonic current distortion factor THDIR (%)
Single-phase 2-wire
1P2W
Single-phase 3-wire
1P3W
Three-phase 3-wire
3P3W2M
Three-phase 3-wire
3P3W3M
Three-phase 4-wire
3P4W
THDIR1
THDIR4
THDIR1
THDIR2
THDIR4
THDIR1
THDIR2
THDIR4
THDIR1
THDIR2
THDIR3
THDIR4
THDIR1
THDIR2
THDIR3
THDIR4
• Calculate the Discrete Fourier Transform of harmonic RMS current at 2048 points (about once every 10
cycles at 50 Hz or every 12 cycles at 60 Hz).
• In the equation above, K indicates the total of orders analyzed.
• Select either THDIF or THDIR to calculate the total harmonic current distortion factor.
c: measured channel, k: order for analysis
T
HDIRc
I
ck()
2
k2=
K
∑
Ick()
2
k1=
K
∑
---------------------
100×=
Harmonic voltage phase angle θUk (deg)
Single-phase 2-wire
1P2W
Single-phase 3-wire
1P3W
Three-phase 3-wire
3P3W2M
Three-phase 3-wire
3P3W3M
Three-phase 4-wire
3P4W
θ U1k
θ U4k
θ U1k
θ U2k
θ U4k
θ U12k
θ U32k
θ U4k
θ U12k
θ U23k
θ U31k
θ U4k
θ U1k
θ U2k
θ U3k
θ U4k
• Calculate the Discrete Fourier Transform of harmonic RMS voltage at 2048 points (about once every 10
cycles at 50 Hz or every 12 cycles at 60 Hz).
• Three-phase 3-wire indicates the result of harmonic calculation with line-to-line voltage.
• Corrects the PLL source fundamental wave to 0° and displays the harmonic voltage phase angle.
• When Uckr=Ucki=0
θ Uk=0°.
• The harmonic voltage used in calculations is only taken from integral harmonics.
c: measured channel, k: order for analysis, r: resistance after FFT, i: reactance after FFT
θUck
Uckr
Ucki–
--------------
⎩⎭
⎨⎬
⎧⎫
1–
tan=
Harmonic current phase angle θIk (deg)
Single-phase 2-wire
1P2W
Single-phase 3-wire
1P3W
Three-phase 3-wire
3P3W2M
Three-phase 3-wire
3P3W3M
Three-phase 4-wire
3P4W
θ I1k
θ I4k
θ I1k
θ I2k
θ I4k
θ I1k
θ I2k
θ I4k
θ I1k
θ I2k
θ I3k
θ I4k
θ I1k
θ I2k
θ I3k
θ I4k
• Calculate the Discrete Fourier Transform of harmonic RMS current at 2048 points (about once every 10
cycles at 50 Hz or every 12 cycles at 60 Hz).
• Corrects the PLL source fundamental wave to 0° and displays the harmonic current phase angle.
• When Ickr=Icki=0
θ Ik=0°.
• The harmonic current used in calculations is only taken from integral harmonics.
c: measured channel, k: order for analysis, r: resistance after FFT, i: reactance after FFT
θIck
Ickr
Icki–
----------- -
⎩⎭
⎨⎬
⎧⎫
1–
tan=