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2-12
IM 760201-01E
Scaling (See sections 4.5 and 4.6 for operating instructions)
When applying current signals through an external current sensor or applying voltage or
current signals through an external VT (voltage transformer) or CT (current transformer),
the conversion ratio or coefficient can be specified.
When Applying Current Signals through an External Current Sensor
The output of current sensors that output voltage, such as shunts and clamps, can be
applied to the current sensor connector (EXT) and measured. Set how many millivolts
the current sensor transmits when 1 A of current is applied (conversion ratio). Then, the
input signal can be made to correspond to the numeric data or waveform display data
that is obtained when the current is directly applied to the input terminals.
Measurement Function
Conversion
Ratio
Data before
Transformation
Transformation
Result
Current I
E
I
S
(current sensor output)
I
S
/E
Active power P
E
P
S
P
S
/E
Apparent power S
E
S
S
S
S
/E
Reactive power Q
E
Q
S
Q
S
/E
Max./Min. current value Ipk
E
Ipk
S
(current sensor output) Ipk
S
/E
When Applying Voltage or Current Signals through an External VT or CT
• VT ratio and CT ratio
You can convert the input signal into the numeric data or waveform display data of the
voltage or current before transformation by setting the VT ratio, CT ratio, and power
factor (coefficient multiplied to the power determined from the voltage and current).
• Power factor
By setting the power factor (SF), you can display the measured active power, apparent
power, and reactive power after they have been multiplied by a coefficient.
Measurement Function
Data before
Transformation
Transformation Result
Voltage U
U
2
(secondary output
voltage of the VT)
U
2
×V
V: VT ratio
Current I
I
2
(secondary output of
the CT)
I
2
×C
C: CT ratio
Active power P
P
2
P
2
×V×C×SF
SF: Power factor
Apparent power S
S
2
S
2
×V×C×SF
Reactive power Q
Q
2
Q
2
×V×C×SF
Max./Min. voltage value Upk Upk
2
(secondary output
of the VT)
Upk
2
×V
Max./Min. current value Ipk
Ipk
2
(secondary output of
the CT)
Ipk
2
×C
2.3 Measurement Conditions
Содержание WT500
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