Technical
Specifications
Copyright © Itech Electronics Co., Ltd.
48
difference
(°)
between voltage and
current of Kth harmonic\
φU(k): voltage phase
difference Kth
harmonic(UK) and
fundamental wave(U1)
φI(k): phase difference
current phase difference
between Kth harmonic(IK)
and fundamental wave(I1)
difference
harmonic
distortion
factor (%)
Uhdf(k): Voltage ratio of Kth harmonic(Uk) and
fundmental wave(U1) or total distortion
wave(Utotal)
Ihdf(k): current ratio of Kth harmonic
（
Ik
）
and
fundmental wave(I1
）
or total distortion wave(Itotal)
Phdf(k): active power ratio of Kth harmonic(Pk)and
fundmental wave or total distortion wave(Ptotal)
(THD)total
harmonic
distortion
(%)
Uthd: voltage ratio of total harmonic and
fundmental
wave(U1) or total distortion
wave(Utotal)
Ithd: current ratio of total harmonic and fundmental
wave(I1) or total distortion wave(Itotal)
Pthd: active power ratio of total harmonic and
fundmental wave(P1) or total distortion
wave(Ptotal)
Window
function
Rectangle
Note: K is a integer from 0 to upper limit of harmonic analyse times.0th means DC parameter. User can
configure the maximum number of harmonic times manually or auto-decided by equipment, taking the
minmum value between the two methods. IT9121 can measure up to 50th harmonic
.
.
8.9 Fundamental Frequency
Fundamental
frequency
sample rate
window width
upper limit of*
analysis orders*
10Hz ~ 75Hz
f*1024
1
50
75Hz ~ 150Hz
f*512
2
32
150Hz ~ 300Hz
f*256
4
16
300Hz ~ 600Hz
f*128
8
8
600Hz ~ 1200Hz
f*64
16
4
*the upper limit of analysis orders can be decrease
8.10 Accuracy
*When line filter is off, the accuracy shown below is the sum of reading and
range errors.
Frequency
Voltage
Current
Power
10Hz
≤
f<45Hz
0.15% of reading
+0.35% of range
0.15% of reading
+0.35% of range
0.15% of reading
+0.50% of range
