ABB Relion REB500 Product Manual page 13

ABB
Distributed busbar protection REB500
Product version: 8.2
Diagram of busbar
I I
1 2
Operating characteristic
180°
external fault
Dj
74°
max
internal fault
0°
Case
1 2
Figure 10. Characteristic of the phase comparator for determining energy direction
Breaker failure protection
The breaker failure functions in the bay units monitor both
phase currents and neutral current independently of the
busbar protection. They have two timers with individual
settings. Operation of the breaker failure function is
enabled either:
· internally by the busbar protection algorithm (and, if
configured, by other local protection functions)
· externally via a binary input, e.g. by the line protection,
transformer protection etc.
· via the station bus using GOOSE signals of other IEDs.
After the delay of the first timer has expired, a tripping
command can be applied to a second tripping coil on the
circuit-breaker and a remote tripping signal transmitted to
the station at the opposite end of the line.
This first timer operates in a stand-alone mode in the bay
unit.
If the fault still persists at the end of the second time
delay, the breaker failure function uses the busbar replica
to trip all the other feeders supplying the same section of
busbar via their bay units.
A remote tripping signal can be configured in the software
to be transmitted after the first or second timer.
Phase-segregated measurements in each bay unit allow
for correct behavior in case of evolving faults.
End fault protection
In order to protect the "dead zone" between an open
circuit-breaker and the associated CTs, a signal derived
from the breaker position and the close command is
applied.
The end fault protection is enabled a certain time after the
circuit-breaker has been opened. In the event of a short
circuit in the dead zone the adjacent circuit-breakers are
tripped.
j
Case 1: external faut = 139°
12
Im
j
= 139°
12
I
2
I
Re
1
j
Case 2: internal fault = 40°
12
Im
= 74°
Re
I
1
j
I
2
= 40°
12
Overcurrent function
A definite time overcurrent back-up protection scheme can
be integrated in each bay unit. (The operation of the
function, if parameterized, may start the local breaker
failure protection scheme.)
Current release criteria
The current release criterion is only performed in the bay
unit. It is effective for a busbar protection trip and for an
intertripping signal (including end fault and breaker failure)
and prevents those feeders from being tripped that are
conducting currents lower than the setting of the current
release criteria.
Voltage release criteria
The voltage criteria are measured in the bay unit. The
function can be configured as release criterion per zone
through internal linking in the central unit.
This necessitates the existence of one set of voltage
transformers per zone in one of the bay units. Tripping is
only possible if the voltage drops below (U<) and / or
exceeds (U >) the set value.
0
Additionally this release criterion can be configured for
each feeder. For details see Table 32.
Check zone criterion
The check zone algorithm can be used as a release
criterion for the zone-discriminating low-impedance
busbar protection system. It is based on a stabilized
differential current measurement, which only acquires the
feeder currents of the complete busbar. The isolator /
breaker positions are not relevant for this criterion.
Neutral current detection I
0
Earth fault currents in impedance-grounded systems may
be too low for the stabilized differential current and phase
comparison functions to detect. A function for detecting
the neutral current is therefore also available, but only for
single phase-to-earth faults.
1MRK 505 352-BEN
Issued: 2016-03-01
Revision: -
13