ABB RELION 670 Series Applications Manual page 128

Section 6
Differential protection
152
252
352
ANSI11000240 V1 EN-US
Figure 59: Example of breaker-and-a-half station
All breakers are normally closed. The requirement for the 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, all circuit breakers associated with the faulty busbar have to be
tripped, but the supply to any load will not be interrupted. The breaker failure protection tripping
logic also needs careful design.
This type of busbar arrangement can be very easily protected. The most common setups for this
type of station are described in the following table.
Table 18:
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 breaker-and-a-half station including internal
CBF protection for middle breaker is given in figure 60.
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152
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352
Typical solutions for breaker-and-a-half stations when CBF for middle breaker is not required
18 is given for the preconfigured versions of REB670 which do not contain
152
152
252 252
352 352
Number of diameters
in the station
2/4
4/8
6/12
6/12
12/24
1MRK 505 337-UUS A
ZA
152
252
352
ZB
ANSI11000240-1-en.vsd
Number of REB670 IEDs required for the
scheme
1/2
1/2
3/6
3/6
3/6
Application manual