ABB RELION 670 Series Applications Manual page 112

Section 6
Differential protection
ANSI04000283 V1 EN-US
Figure 46: Example of station without main CTs in the bus-section bay
In such case two separate zones can be maintained only while bus coupler breaker is open. As
soon as bus coupler breaker is going to be closed the zone interconnection feature must be
activated and complete busbars will be automatically protected with just one overall differential
zone.
Since there are no current transformer in the bus coupler bay, there is no need to allocate internal
bay function block for the bus coupler bay. However some additional configuration logic is
required to obtain automatic zone interconnection activation when bus coupler breaker shall be
closed. Example of such logic, as shown in figure 47.
289
189
Bus coupler
ANSI06000137 V1 EN-US
Figure 47: Configuration logic for bus coupler without main CTs
106
ZA
1 2 10
Zone A
Zone B
REB 670
BIM
0-tOFF
52b
152
BS
ZB
1 2
ZI
AND NOT
EXTSTART
1MRK 505 337-UUS A
10
en04000283_ansi.vsd
BOM
ACTIVE
ALARM
Indication that
Zone interconnection
is active
en06000137_ansi.vsd
Application manual