YOKOGAWA WT210, Руководство пользователя, Страница: 301 / 316

16-6
IM 760401-01E
Item Specifications
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 of 500 Hz).
Accuracy Requirements
• The amplitude of the measure signal is at least 30% (greater than or equal to 60% if the crest
factor is set to 6) of the rated value of the voltage or current range.
• Frequency filter is ON when measuring voltage or current of 200 Hz or less.
Accuracy
±
(0.06% of reading)
Computation
Item Specifications
Computing equation of apparent power (VA), reactive power (var), power factor (PF), and phase angle (deg)
Wiring System
Single-phase,
two-wire
Active Power (W)
W
Apparent Power (VA)
VA=V•A
cos–
1
( )
Reactive Power (var) Power Factor (PF) Phase Angle (deg)
W
VA
2
W
VA
Single-phase,
three-wire
(i=1, 3)
W
i
Σ
W=W
1+
W
3
Σ
W=W
1+
W
2+
W
3
VA
i
=V
i•
A
i
var=
PF=
Σ
VA=VA
1+
VA
2+
VA
3
Σ
VA=VA
1+
VA
3
Σ
var=var
1+
var
2+
var
3
(VA)
2–
W
2
i: Input element number
deg=
Three-phase,
three-wire
(i=1, 3)
W
i
Σ
W=W
1+
W
3
VA
i
=V
i•
A
i
var
i
=
W
i
VA
i
PF
i
=
Σ
W
Σ
VA
Σ
PF=
Σ
VA= (VA
1+
VA
3
)
Σ
var=var
1+
var
3
(VA
i
)
2–
W
i
2
cos
–1
( )
W
i
VA
i
deg
i
=
cos
–1
( )
Σ
W
Σ
VA
Σ
deg=
3
3
3
Three-phase,
four-wire
(i=1, 2, 3)
W
i
VA
i
=V
i•
A
i var
i
= (VA
i
)
2–
W
i
2
Σ
W=W
1+
W
3
Σ
VA= (VA
1+
VA
2
+VA
3
)
Σ
var=var
1+
var
3
Three-voltage,
three-current
(i=1, 2, 3)
W
i
(W
2 has no physical
meaning)
VA
i
=V
i•
A
i var
i
= (VA
i
)
2–
W
i
2
Note
• The WT210/WT230 computes apparent power (VA), reactive power (var), power factor (PF),
and phase angle (deg) from voltage, current, and active power through digital computation. If
distorted signal is input, the value obtained on this instrument may differ from that obtained on
other instruments using a different measurement principle.
• If the voltage or current is less than 0.5% (less than or equal to 1% if the crest factor is set to
6) of the rated range, zero is displayed for VA or var, and error is displayed for PF and deg.
• The accuracy of detecting lead or lag is defined for a voltage and current input that is at least
50% (range rating if the crest factor is set to 6) of the rated range.
Detection accuracy:
±
5 deg (20 Hz to 2 kHz)
• For
±Σ
var computation, when the current leads the voltage, each var value is computed as a
negative value; when the current lags the voltage, the value is computed as a positive value.
16.3 Functions