ABB REB670 Applications Manual page 163

1MRK 505 337-UUS -
Application manual
Table 25: Functions
Functions
Busbar Differential Protection
Dynamic Zone Selection feature
CCRBRF/CCSRBRF function
OC4PTOC/PHS4PTOCfunction
OC4PTOC/PHS4PTOC function
DRPRDRE function
DRPRDRE function
Table continues on next page
Differential protection
Comment
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.
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.
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.
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.
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.
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.
Event List feature in the IED can be used in the exactly the
same way as with phase segregated design.
Section 6
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