Output Mode; Application; Input Scaling - ABB RELION REX640 Technical Manual

1MRS759142 C
3.15.3.2
3.15.4
3.15.4.1
REX640
Technical Manual
When necessary, the valid measuring range may be narrower than the default of the
selected measuring range. A narrower range can be defined with the Value minimum
and Value maximum settings.

Output mode

A measurement value from another function, mA input or RTD input can be
represented by the mA output. The mA output scaling principle is otherwise similar to
the input scaling but there is also a possibility to use up to four different knee points.
To be able to cover a wide range of input units, the input settings used for scaling are
dimensionless. The output range of the mA output is selected with parameters Value
maximum and Value minimum and the selected number of knee points with parameter
Num of knee points. Depending on the amount of Num of knee points, the knee point
settings Input knee point 1-4 and Value knee point 1-4 are visible.
Table 85: Analog output modes for the mA outputs 1 and 2
Output mode
Not in use
-20...20 mA

Application

The general function block can be used in REX640 relays that are equipped with an
RTD/analog module.
The function can be applied to various applications, for example, to measure
temperature, pressure or flow.

Input scaling

Each mA/RTD input can be scaled linearly by constructing a separate scaling curve
for each input. The curve consists of two points where the x-axis of the curve
illustrates a range selected for the input and the y-axis is the scaled absolute value of
the input. The input scaling is enabled only when mA or resistance input is used.
When the scaling is enabled, the settings Value maximum and Value minimum affect
the scaled range. The range of the scaled input is defined with the settings Input
minimum and Input maximum.
Scaling example 1
The function is used with a Pt100 temperature sensor. Predefined scaling can be
selected when Input mode is set to "Pt100".
Basic functions
Description
Default selection when the corresponding output
is not used
Analog output can operate in the range of -20...20
mA.
The output can be used in a narrower range by
Value minimum and Value maximum .
setting
Section 3
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