YOKOGAWA WT332E - Page 123

7-10
IM WT310E-02EN
7.4.2 Frequency Measurement
Item Specifications
Measured item Voltage and current frequencies applied to the selected input element can be measured.
WT332E (two element model)
Select voltage (U1)/current (I1) of input element 1 or voltage (U3)/current (I3) of input element 3.
WT333E (three element model)
Select voltage (U1)/current (I1) of input element 1, voltage (U2)/current (I2) of input element 2 or
voltage (U3)/current (I3) of input element 3.
Method Reciprocal method
Frequency measuring range Varies depending on the data update interval (see description given later) as follows:
Data Update Interval Measurement Range
0.1s 20Hz≤f≤100kHz
0.25s 10Hz≤f≤100kHz
0.5s 5Hz≤f≤100kHz
1s 2.0Hz≤f≤100kHz
2s 1.0Hz≤f≤100kHz
5s 0.5Hz≤f≤100kHz
10s 0.2Hz≤f≤100kHz
20s 0.1Hz≤f≤100kHz
Auto* 0.1Hz≤f≤100kHz
* Limit of the measurement lower limit frequency by the Timeout setting
Timeout : lower limit frequency
1 s 2.0 Hz
5 s 0.5 Hz
10 s 0.2 Hz
20 s 0.1 Hz
Only for the direct current input of the WT310EH, the maximum measurement range is 20 kHz.
Measurement range Auto switching among six types: 1 Hz, 10 Hz, 100 Hz, 1 kHz, 10 kHz, and 100 kHz
Frequency filter Select OFF or ON (cutoff frequency at 500 Hz).
Accuracy Requirements
• When the input signal level is 30% or more of the measurement range if the crest factor is set
to 3 (60% or more if the crest factor is set to 6 or 6A)
• Frequency filter is ON when measuring voltage or current of 200 Hz or less.
Accuracy: ±(0.06% of reading)
7.4.3 Computation
Item Specifications
Computingequationofapparentpower(S),reactivepower(Q),powerfactor(λ),andphaseangle(Φ)
i : Input element number
Single-Phase, Three-
Wire (1P3W)
Three-Phase, Three-
Wire (3P3W)
Three-Phase, Three-
Wire (3V3A)
Three-Phase, Four-
Wire (3P4W)
UΣ[V] (U1+U3)/2 (U1+U2+U3)/3
IΣ[A] (I1+I3)/2 (I1+I2+I3)/3
PΣ[W] P1+P3 P1+P2+P3
SΣ[VA] Si=Ui×Ii S1+S3
)
31(
2
3
SS +
)
321(
3
3
SSS ++
S1+S2+S3
QΣ[var]
Qi=
22
ii
PS −
Q1+Q3 Q1+Q2+Q3
λΣ λi=Pi/Si
S
PΣ
Σ
Φ[°]
Φi=
)
(
c
os
1
i
i
S
P
−
)
(
c
os
1−
S
PΣ
Σ
7.4 Features