ABB RELION 670 Series Applications Manual page 137

1MRK 505 337-UUS A
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:
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
Please note that table
any VT inputs.
Note that for station layouts where combined transfer and bus-coupler bay is used, as for example
is shown in figure 68, two internal bay function blocks must be allocated to such primary bay,
reducing number of available feeder bays. In such station maximum available number of feeder
bays is less for one from the values shown in table 21, on condition that just one main CT is
available from Bus-Coupler/Transfer bay. For station with just one CT in the bus-coupler bay, it
might be required, depending on the client requirements, to provide the logic scheme for
disconnection of bus-coupler CT when the bus-coupler CB is open. For more information, refer to
figure 45.
6.1.4.11 Combined busbar arrangements
There are stations which are practically a combination between two normal types of station
arrangements, which are already previously described. Some typical examples will be shown here:
Application manual
Possible solutions for double busbar-single breaker with transfer bus arrangements
21 is given for the preconfigured versions of REB670 which do not contain
Total number of Number of REB670 IEDs required for
feeder bays in the the scheme
station (excluding
buscoupler & bus-
section bays)
NA NA
1
)
7*
NA NA
3
)
11*
3
)
23*
Section 6
Differential protection
M6650-3 v4
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