YOKOGAWA WT500 User Manual page 114

4.6 Setting the Scaling Feature When Using a VT or CT
Explanation
4-18
Set the VT ratio when applying the secondary output of a VT to the voltage input
terminal. Then, set the voltage range according to the maximum VT output (see section 4.4
for instructions). In addition, set the CT ratio (or the conversion ratio of the current sensor
that produces current) when applying the secondary output of a CT or clamp-type current
sensor that produces current to the current input terminal. Then, set the current range
according to the maximum current sensor output. For details, see section 2.3.
Turning the Scaling Feature On or Off
You can select whether to multiply the applicable measurement functions by the VT ratio,
CT ratio, or power factor. When reading measured values directly by using a VT or CT (or
current sensor), select ON. The Scaling indicator lights when ON is selected.
Applicable measurement functions:
• ON: The measurement functions above are multiplied by the VT ratio, CT ratio, or
power factor.
• OFF: The measurement functions above are not multiplied by the VT ratio, CT ratio,
or power factor. The output values of the VT and CT are displayed directly as
numeric data.
Setting the VT Ratio
The ratio can be set to a value from 0.0001 to 99999.9999.
Setting the CT Ratio
The ratio can be set to a value from 0.0001 to 99999.9999.
Setting the Power Factor (SF, Scaling Factor)
The factor can be set to a value from 0.0001 to 99999.9999.
Note
• If the value of the result of multiplying the measured value by the VT ratio, CT ratio, or power
factor (scaling factor) exceeds 9999.9M, "-OF-" will appear in the numeric data display
frame.
• For information about how to display a list of the VT and CT ratios and power factors of all
input elements, see section 3.17, "Displaying a List of Setup Parameters." When the scaling
feature is off, the list displays 1.0000 for all VT and CT ratios and power factors.
• To correctly compute the power and efficiency of
elements so that all power units used in the computation are the same. For example, the
efficiency cannot be computed correctly if elements or wiring units used in the computation
have different power units, such as W (watt) and J (joule). To compute the efficiency
correctly, make all of the power units the same (either all W or all J).
Voltage (U), current (I), power (P, S, and Q),
maximum and minimum voltages (U+pk and
U-pk), and maximum and minimum currents
(I+pk and I-pk)
Σ
functions, set the power factors of all
IM 760201-01E