ABB REB670 Applications Manual page 143

1MRK 505 337-UUS -
Application manual
152 152
252 252
352 352
ANSI11000240 V1 EN
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: Typical solutions for breaker-and-a-half stations when CBF for middle breaker is not
required
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 18
contain any VT inputs.
152
252
352
Number of diameters in
the station
2/4
4/8
6/12
6/12
12/24
is given for the preconfigured versions of REB670 which do not
Section 6
Differential protection
152 152
252 252
352 352
ANSI11000240-1-en.vsd
Number of REB670 IEDs
required for the scheme
1/2
1/2
3/6
3/6
3/6
ZA
ZB
137