ABB REB670 - Page 177

Table 25: Functions
Functions Comment
Busbar Differential Protection Differential Protection, Sensitive differential protection, OCT
algorithm, Check Zone and Differential Supervision features
will be connected to the summated bay currents. Therefore,
they will have different
level depending on the type of fault
and involved phase(s). For more information, refer to
Table 24. However, if all these limitations are acceptable it is
still possible to use all these internal busbar protection
features. Note that OCT operating logic will not work properly
in case of opening or shorting the main CT secondary leads
(that is, in-between main CT and ASCT). In case of opening
or shorting the ASCT secondary leads (that is, in-between
ASCT and the IED) the OCT logic will operate correctly.
Dynamic Zone Selection feature Zone Selection feature in the IED can be used in the exactly
same way as with phase segregated design. All built-in
features, even including breaker failure protection, protection
back-up trip command routing, EnFP logic can be used in the
exactly same way as for phase segregated design.
CCRBRF/CCSRBRF function Breaker Fail Protection function will be connected to the
summated bay current. Therefore it will have different
pickup
level depending on the type of fault and involved phase(s).
See Table 24 for more info. It will not be possible to have
individual initiation per phase, but only three-phase initiation
can be effectively used. However, if all these limitations are
acceptable it is still possible to use internal CCRBRF/
CCSRBRF functions.
OC4PTOC/PHS4PTOCfunction Overcurrent Protection function will be connected to the
summated bay current. Therefore, it will have different pickup
level depending on the type of fault and involved phase(s).
See Table 24 for more info. Thus it will be very difficult to
insure proper pickup
and time grading with downstream
overcurrent protection relays. Hence it will be quite difficult to
use OC4PTOC/PHS4PTOC as backup feeder protection with
summation design.
OC4PTOC/PHS4PTOC function End Fault Protection feature will be connected to the
summated bay current. Therefore it will have different pickup
level depending on the type of fault and involved phase(s).
See Table
24 for more info. However, OC4PTOC/
PHS4PTOC do not need any pickup or time coordination with
any other overcurrent protection. Thus if above limitations are
acceptable
OC4PTOC/PHS4PTOC can be used with
summation design.
DRPRDRE function Disturbance Recording feature will be connected to the
individual summated bay current. Therefore recorded
currents will not correspond to any actual primary currents.
However such DRPRDRE records can still be used to
evaluate internal busbar protection, CCRBRF/CCSRBRF and
OC4PTOC/PHS4PTOC protections operation.
DRPRDRE function Event List feature in the IED can be used in the exactly the
same way as with phase segregated design.
Table continues on next page
1MRK 505 370-UUS A Section 6
Differential protection
Busbar protection REB670 2.2 ANSI 171
Application manual