ABB RELION 670 SERIES REG670 Applications Manual page 191

1MRK 502 071-UUS A
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual
AddTripDelay: If the input DESENSIT is activated the operation time of the protection
function can also be increased by the setting AddTripDelay.
OperDCBiasing: If enabled the DC component of the differential current will be
included in the bias current with a slow decay. The option can be used to increase
security if the primary system DC time constant is very long, thus giving risk of
current transformer saturation, even for small currents. It is recommended to set
OperDCBiasing = Enabled if the current transformers on the two sides of the generator
are of different make with different magnetizing characteristics. It is also
recommended to set the parameter OperDCBiasing = Enabled for all shunt reactor
applications.
The DC component is always calculated from the instantaneous differential current for
each phase in primary Amperes. The value of DC component can be read from
function outputs: IDDCL1, IDDCL2 and IDDCL3. For special purpose, the DC
component from phase currents can also be calculated by GENPDIF function. In this
case, only one current group should be connected to GENPDIF and the rest current
group inputs should be connected to GRP_OFF as shown in Figure 71.
IEC17000047 V1 EN-US
Figure 71: GENPDIF connection
Section 7
Differential protection
IEC17000047-1-en.vsdx
185