YOKOGAWA WT110 User Manual page 45

Explanation
IM 253401-01E
4.4 Setting the Scaling Value when External PT/CT is Used
About the Scaling Function
This function is useful for measuring voltage, current, power and such when you are using an
external potential transformer (PT), current transformer (CT) or such, and have connected their
secondary side outputs to the input elements. You set the scaling value to the PT ratio, CT ratio
or power factor. When the scaling function is turned ON, measured values which have been
converted to the corresponding values for the transformer primary sides, can been displayed or
otherwise output.
Measured/computed value
Voltage V
Current A
Active power W
Reactive power var
Apparent power VA
Selecting the Input Element
This setting is to select to which element scaling will be applied. The initial value is "ALL". At
the WT110, this selection menu will not appear.
• ALL : Select this when the same scaling values should be applied to all elements together.
• EL1 : Select this when the scaling values should only be applied to element 1.
• EL2 : Select this when the scaling values should only be applied to element 2. This selection
will not appear on model 253502.
• EL3 : Select this when the scaling values should only be applied to element 3.
• End : Select this when you finished the setting, or when you want to abort the setting.
Setting the Scaling Value
The scaling values are set in the following order. The setting ranges from 0.001 to 1000. The
initial value is 1.000.
• P : Sets the PT ratio on display A
• C : Sets the CT ratio on display B
• F : Sets the power value on display C
In case of the WT110, pressing the ENTER key after setting P, C and F respectively will end
this scaling setting. In case of the WT130, selecting End at the input element menu will end this
scaling setting.
Turning Scaling ON/OFF
Select the scaling menu once again after having set the scaling values. The initial value is oFF.
• on : When this setting is selected, pressing the ENTER key will start scaling and the
SCALING indicator will light.
• oFF : When this setting is selected, pressing the ENTER key will stop scaling and SCALING
indicator will extinguish.
Note
When the scaling value x measurement range exceeds 9999M, the computation over display will appear
(refer to page 2-3).
Scaled result
P × V
P: Voltage scaling value
C × A
C: Current scaling value
F × P × C × W
F: Power scaling value
F × P × C × var
F × P × C × VA
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