ABB RELION RET670, Applications Manual

Page: 867 / 1016

EqualBandLow : This setting is used to set the equal condition low band limit in % of
reference value. This low band limit will act as reset limit for INLOW output when
INLOW.
17.14.4 Setting example
GUID-E7070CF6-B44B-4799-BE18-5C75B9FE2A87 v2
Let us consider a comparison is to be done between current magnitudes in the range of
90 to 110 with nominal rating is 100 and the order is kA.
For the above condition the comparator can be designed with settings as follows,
EnaAbs = Absolute
RefSource = Set Value
SetValue = 100
RefPrefix = Kilo
EqualBandHigh = 5.0 % of reference value
EqualBandLow = 5.0 % of reference value
Operation
The function will set the outputs for the following conditions,
INEQUAL will set when the INPUT is between the ranges of 95 to 105 kA.
INHIGH will set when the INPUT crosses above 105 kA.
INLOW will set when the INPUT crosses below 95 kA.
If the comparison should be done between two current magnitudes then those current
signals need to be connected to function inputs, INPUT and REF. Then the settings
should be adjusted as below,
EnaAbs = Absolute
RefSource = Input REF
EqualBandHigh = 5.0 % of reference value
EqualBandLow = 5.0 % of reference value .
1MRK 504 163-UUS A
Section 17
Logic
Transformer protection RET670 2.2 ANSI 861
Application manual