ABB REB670 Applications Manual page 152

Section 6
Differential protection
146
ZA
ZB
189
289 789 189 289
152
152
ANSI06000015 V1 EN
Figure 68: Example of double busbar-single breaker with transfer bus arrangement
This type of busbar arrangement is very common in some countries. It provides good
balance between maintenance work requirements and security of supply. If needed, two
busbars can be split during normal service. Additionally any feeder CB can be taken out
for maintenance without interruption of supply to the end customers connected to this
feeder.
The requirement for busbar protection scheme is that the scheme must have two
independent differential zones, one for each busbar. In case of an internal fault on one of
the two buses, bus-coupler circuit breaker and all feeder circuit breakers associated with
the faulty bus have to be tripped, leaving other busbar still in normal operation. When
transfer bus is in operation it will be protected as an integral part of one of the two
internally available zones. Special attention shall be given that appropriate logic for zone
selection is done with help of graphical configuration tool. At the same time, load transfer
and possible transfer of trip signals from the feeder under transfer to the transfer circuit
breaker shall be arranged in appropriate way as well. This type of busbar arrangement can
be protected as described in the following table:
Table 21: Possible solutions for double busbar-single breaker with transfer bus arrangements
Version of REB670 IED
3PH; 2-zones, 4-bays BBP (A20)
3PH; 2-zones, 8-bays BBP (A31)
1Ph; 2-zones, 12-bays BBP (B20)
1Ph; 2-zones, 12-bays BBP (B21)
1Ph; 2-zones, 24-bays BBP (B31)
)
* with one set of CTs in bus-coupler bay and separate transfer and bus-coupler breaker
789
189 289 789 2089
152
Total number of feeder
bays in the station
(excluding buscoupler &
bus-section bays)
NA
)
7*
NA
)
11*
)
23*
1MRK 505 337-UUS -
789
189 289 189 289
152
152
xx06000015_ansi.vsd
Number of REB670 IEDs
required for the scheme
NA
1
NA
3
3
Application manual
789