Input Linear Scaling - ABB RELION 620 Series Technical Manual

Section 3
Basic functions
3.11.2.3
100
possible, but the default range (0...20 mA) can be set smaller with the Value maximum and
Value minimum settings.
When the channel is used for resistance type signals and the application requires a linear
scaling of the input range, the Value unit setting value has to be "Dimensionless", where
the input range can be linearly scaled with the setting Input minimum and Input maximum
to Value minimum and Value maximum. When resistance is used as an output unit, Value
unit has to be "Ohm". When Value unit is set to "Ohm", the linear scaling is not possible,
but the default range (0...2000 Ω) can be set smaller with the Value maximum and Value
minimum settings.

Input linear scaling

Each RTD/mA input can be scaled linearly by the construction of a linear output function
in respect to the input. The curve consists of two points, where the y-axis (Input minimum
and Input maximum) defines the input range and the x-axis (Value minimum and Value
maximum) is the range of the scaled value of the input.
The input scaling can be bypassed by selecting Value unit = "Ohm" when
Input mode = "Resistance" is used and by selecting Value unit = "Ampere"
when Input mode = "0...20 mA" is used.
Example for linear scaling
Milliampere input is used as tap changer position information. The sensor information is
from 4 mA to 20 mA that is equivalent to the tap changer position from -36 to 36,
respectively.
X130-Input#
20 mA
Input maximum
"0..20mA"
Input mode
4 mA
Input minimum
-36
Value minimum
GUID-85338A5E-3D2F-4031-A598-EA8A525190D3 V1 EN
Figure 31: Milliampere input scaled to tap changer position information
"Dimensionless"
Value unit
1MAC504801-IB E
AI_VAL#
36
Value maximum
620 series ANSI
Technical Manual