ABB REL 356 Current Differential Protection
3-6
Settings and Application
The settings are summarized in the table below where TRIP is trip from the local relay (differential or back-up trip) and
TTRP is received transfer trip from the remote end:
DDTT
TRIP-1/BFI-1
TRIP-2/BFI-2
TRIP-3/BFI-3
TRIP-4/BFI-4
TRIP-5/BFI-5
TRIP-6/BFI-6
0
TRIP/TTRP
TRIP/TTRP
TRIP/TTRP
TRIP/TTRP
TRIP/TTRP
TRIP/TTRP
2
TRIP
TRIP
TRIP
TRIP
TTRP
TTRP
4
TRIP
TRIP
TTRP
TTRP
TTRP
TTRP
Low Set Current Supervision (ILTS)
The user can select to supervise differential trip but the low set current elements, IPL and IGL. With ILTS = IN, higher
security is achieved. However, for weak feed applications when the local fault current may not exceed the set IPL or IGL
current levels, ILTS should be set to OUT in order to allow the weak terminal to trip on current differential operation.
Reclose Block Enable (RBEN)
The following settings are provided for system flexibility:
NORB
Normal Reclose Block. The RB contacts will close for the following trips:
·
Reclose into fault
·
Trip from the back-up system
·
Out-of-step trip
·
High set overcurrent trip
·
Transfer trip
ALRB
All Reclose Block. The RB contacts will close for all trips.
Stub/Open Breaker Timer (SOBT)
The SOBT timer provides a time delay for the stub bus and open breaker trip functions. When using 52b inputs for the
open breaker detection, the reset time of the breaker contacts should be carefully considered. If the contact reset time
is greater than the set SOBT time, reclosing will be unsuccessful. The reason is as follows: after a trip, with both
breakers open, one end closes back into the line successfully. The second end closes in but has slow resetting 52b
contacts why OPBR (open breaker) code is still being received by the remote end at the time load current starts to flow.
The remote end will then trip from the low set IPL elements if OPBK function is used. The SOBT timer thus needs to be
set longer than the 52b contact reset time plus channel delay plus 8 msec margin.
The 52b contact reset time is generally close to zero when the breaker contacts are used directly but might be much
longer when connected to the relay via an external auxiliary relay.
For example: Set SOBT = 20 msec for a digital channel with 1.3 msec channel delay and 52b auxiliary contact reset
time of 10 msec.
Open Breaker (OPBR)
The following settings are available for open breaker keying:
·
IE
Keying is initiated when the line current is lower than the IE setting. Note that the line charging current
must exceed this setting, which limits the use of this option on short lines.
·
52B
Keying is initiated when the 52b contact at the local end is closed.
·
BOTH
Keying is initiated either when the load current is lower than the IE setting or when 52b is closed.
Summary of Contents for REL 356
Page 23: ...ABB REL 356 Current Differential Protection 1 10 Product Overview and Specifications ...
Page 83: ...ABB REL 356 Current Differential Protection 3 36 Settings and Application ...
Page 127: ...ABB REL 356 Current Differential Protection 5 28 Testing ...
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