YOKOGAWA WT500 User Manual page 35

2.3 Measurement Conditions
Scaling (See sections 4.5 and 4.6 for operating instructions)
2-12
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
Current I
Active power P
Apparent power S
Reactive power Q
Max./Min. current value Ipk
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
Voltage U
Current I
Active power P
Apparent power S
Reactive power Q
Max./Min. voltage value Upk
Max./Min. current value Ipk
Conversion Data before
Ratio Transformation
E I (current sensor output)
S
E P
S
E S
S
E Q
S
E Ipk (current sensor output) Ipk
S
Data before
Transformation
U (secondary output
2
voltage of the VT)
I (secondary output of
2
the CT)
P
2
S
2
Q
2
Upk (secondary output
2
of the VT)
Ipk (secondary output of
2
the CT)
Transformation
Result
I /E
S
P /E
S
S /E
S
Q /E
S
/E
S
Transformation Result
U ×V V: VT ratio
2
I ×C C: CT ratio
2
P ×V×C×SF SF: Power factor
2
S ×V×C×SF
2
Q ×V×C×SF
2
Upk ×V
2
Ipk ×C
2
IM 760201-01E