ABB RELION 670 Series Applications Manual page 126

Section 6
Differential protection
For station with double zone protection and just one set of CTs in the bus-section bay, it might be
required, depending on the client requirements, to provide the special scheme for disconnection
of bus-section CT when the bus-section CB is open. For more information, refer to figure 45.
6.1.4.6 Double circuit breaker busbar arrangement
The circuit breaker, disconnectors and instrument transformers are duplicated for every feeder, as
shown in figure 57.
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ANSI06000018 V1 EN-US
Figure 57: Example of double breaker station
This is an extremely flexible solution. In normal service all breakers are closed. The requirement for
busbar protection scheme is that the scheme must have two independent differential zones, one
for each busbar. If there is an internal fault on one of the two buses all circuit breakers associated
with the faulty busbar have to be tripped, but supply to any load will not be interrupted. The
tripping logic for the circuit breaker failure protection must be carefully arranged.
The most common setups for this type of busbar arrangement are described in the following
table.
Table 17:
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)
Please note that table
any VT inputs.
A principle overall drawing of how to use REB670 for this type of station is given in figure 58.
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252 152 252
152
Typical solutions for double circuit breaker busbar arrangement
17 is given for the preconfigured versions of REB670 which do not contain
252 252
152 152
xx06000018_ansi.vsd
Numbers of feeders
per station
4
4/8
6/12
6/12
12/24
1MRK 505 337-UUS A
ZA
ZB
252
Number of REB670 IEDs required for the
scheme
2
1/2
3/6
3/6
3/6
Application manual
M6645-3 v4