ABB RED650 - Page 500

comparison is taken from second input signal (REF). If RefSource is selected as Set
Value 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 then
comparison is done. If EnaAbs is selected as Signed then the comparison is done
without absolute conversion.
High
Comparator
Low
comparator
XOR
ABS
INPUT
REF
INHIGH
INEQUAL
INLOW
T
F
ABS
EqualBandHigh
EnaAbs
EqualBandLow
RefSource
SetValue
SetValPrefix
IEC15000130-2-en.vsdx
T
F
T
F
IEC15000130 V2 EN-US
Figure 250: 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.
In order to avoid oscillations at boundary conditions of equal band low limit and
high limit, hysteresis has been provided. If the INPUT is above the equal high level
margin including hysteresis, then INHIGH will set. Similarly if the INPUT is
below the equal low level margin including hysteresis, then INLOW will set.
Section 14 1MRK 505 394-UEN A
Logic
494 Line differential protection RED650 2.2 IEC
Technical manual