4-11
IM 253421-01E
Setting Measurement Conditions and Measurement Range
4
Explanation
Scaling Function in combination with External Sensor Input
This function is useful for measuring current, power and such when you are using an
external sensor, and have connected their output to the input connector. You set the
scaling constant to the current or power value, computed from the sensor. 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. This function is exactly the same as the one described previously
for use with PT/CT.
Measured/computed value
Scaled result
Current A
E
×
A
E: External sensor scaling constant
Active power W
E
×
W
Reactive power var
E
×
var
Apparent power VA
E
×
VA
Selecting the Setting Format of the Scaling Constant
The range is from 0.001 to 9999. The initial value is 50.00. The scaling constant is
specified using display C.
Selecting the Measurement Range (Current, with Scaling function ON)
After having set the scaling constants, select the menu for the current measurement
range. Select the rated output of the external sensor from this menu (see the
Operating Procedure on the previous page). Scaling of the external sensor input will
start as soon as you press the ENTER key after selecting. Scaling will stop as soon
as you select a measurement range other than external sensor input from the menu.
Setting Example of Scaling Constants for External Sensor Input
• In case the rated specs of the external sensor are 50 A/50 mV, measurement
range is 50 mV, then
50 A/50 mV
×
50 mV = 50 A: scaling constant is 50.00
• In case the rated specs of the external sensor are 100 A/50 mV, measurement
range is 50 mV, then
100 A/50 mV
×
50 mV = 100 A: scaling constant is 100.00
• In case the rated specs of the external sensor are 50 A/80 mV, measurement
range is 50 mV, then
50 A/80 mV
×
50 mV = 31.25 A: scaling constant is 31.25
However, since the setting range is 50 mV, use a setting within the 0 to 50 mV
range.
Note
•
When performing measurements using the external sensor, make sure to turn off the scaling
function for the external PT/CT. When this function is ON, the scaling constant of the CT ratio
will interfere.
•
The input range for the external sensor can only be of the manual type.
•
When you switch from external sensor input to direct, auto range input, an error will appear.
First, select manual range for direct input and afterwards select auto range. (same goes for
setting by communication interface.)
4.6 Selecting the Measurement Range and Setting the Scaling Constant when External Sensor is Used (option)
