ABB Relion 670 series - Page 1012

15.17.6 Operation principle
GUID-3FA699A8-D076-4E5E-BCB8-C6B7907573D1 v1
The comparison can be done in two ways,
1. Between 2 inputs, INPUT and REF
2. Between INPUT and the value set by the user SetValue
The selection of reference value for comparison can be done through setting RefSource . If
RefSource is selected as REF then the reference value for comparison is taken from second input
signal (REF). If RefSource is selected as SetValue then the reference value for comparison is taken
from setting ( SetValue ).
Generally the inputs to the function are in SI units, but when the comparison is to be done with
respect to set level, then the user can set a value in any unit out of Milli to Giga range in setting
SetValue . The unit can be separately set with setting RefPrefix . Internally the function handles the
reference value for comparator as SetValue*RefPrefix .
Additionally the comparison can be done either between absolute values or signed values and it
depends on the setting
EnaAbs . If EnaAbs is selected as Absolute then both input and reference
value is converted into absolute values and comparison is done. If
EnaAbs is selected as Signed
then the comparison is done without any conversion.
High
Comparator
Low
comparator
XOR
ABS
INPUT
REF
INHIGH
INEQUAL
INLOW
T
F
ABS
EqualBandHigh
EnaAbs
EqualBandLow
RefSource
SetValue
RefPrefix
T
F
T
F
IEC15000130-1-en.vsdx
IEC15000130 V1 EN-US
Figure 527: Logic diagram for REALCOMP
This function has two settings EqualBandHigh and EqualBandLow to provide margins from
reference value for equal to condition. When the INPUT value is within high and low band, output
INEQUAL will get set.
If the INPUT is above the equal high level margin then output INHIGH will set. Similarly if the INPUT
is below the equal low level margin then output INLOW will set. In order to avoid oscillations at
boundary conditions of equal band low limit and high limit, hysteresis has been provided
Section 15 1MRK 502 066-UUS B
Logic
1006
Technical manual