ABB RELION REX640 - Page 175

200 °C
-40 °C
Input mode
”Pt100”
Input
AI_VAL
Value unit
”Degrees celsius”
Figure 69: Pt100 scaling function
Scaling example 2
Input mode is set to –20...20 mA that is used for tap position information fed from
the tap changer. The tap positions are between –36...36. Thus, the scaling setting
Value minimum is set to "–36" and Value maximum is set to "36". These settings
apply the input scaling to the output. In the tap position case, the Value unit should
be set to "Dimensionless".
Value unit
Value minimum
Value maximum
”Dimensionless”
4 mA
Input mode
”-20..20mA”
36
-36
20 mA
Input
AI_VAL
Input minimum Input maximum
Figure 70: Tap changer position from mA input
Scaling example 3
When Input mode is set to "Resistance", the output can be scaled as desired. For
example, the desired function output is a ratio in a function of resistance. If the
input resistance varies between 100...1600 ohms, Input minimum is set to "100" and
Input maximum is set to "1600". As the wanted output should be in percents, the
setting Value unit is set to "Dimensionless". When Input mode is set to "Resistance",
output scaling is enabled. Thus, Value minimum is set to "0" and Value maximum
is set to "100". These settings allow the input values to be scaled as a ratio of the
resistance range.
1MRS759142 F
Basic functions
REX640
Technical Manual
175