ABB Relion 670 Series Product Manual page 16

Busbar protection REB670
Customized
Product version: 1.2
• Permanently connect this bay current to zone A (that is,
ZA)
• Permanently connect this bay current to zone B (that is,
ZB)
• Permanently connect this bay current to zone A and
inverted bay current to ZB (that is, ZA and ZB)
• Connect this bay current to ZA or ZB depending on the
logical status of the two input binary signals available on
this bay function block. These two input signals will
include measured current to the respective zone when
their logical value is one (that is,
option is used together with above described Switch
function blocks in order to provide complete Zone
Selection logic
• Connect the bay current to ZA or ZB depending on the
logical status of the two input binary signals available on
this bay function block. These two signals will include
measured current to the respective zone when their
logical value is zero (that is,
is typically used when only normally closed auxiliary
contacts from the busbar disconnector are available to
the Zone Selection logic
At the same time, an additional feature for instantaneous or
time delayed disconnection or even inversion of the
connected bay current via separate logical signals is also
available. This feature is provided in order to facilitate for bus-
section or bus-coupler CT disconnection for tie-breakers with
a CT only on one side of the circuit breaker. This ensures
correct and fast fault clearance of faults between the CT and
the circuit breaker within these bays. The same feature can
be individually used in any feeder bay to optimize Busbar
differential protection performance, when feeder circuit
breaker is open. Thus, the end-fault protection for faults
between circuit breaker and the CT is available. However, to
use this feature circuit breaker auxiliary contacts and closing
command to the circuit breaker shall be wired to the binary
inputs of the IED. Therefore, he IED offers best possible
coverage for these special faults between CT and circuit
breaker in feeder and bus-section/bus-coupler bays.
Within the Bay function block it is decided by a parameter
setting how this bay should behave during zone
interconnection (that is, load transfer). For each bay
individually one of the following three options can be selected:
• Bay current is forced out from both zones during zone
interconnection (used for bus-coupler bays)
• Bay current is unconditionally forced into both zones
during zone interconnection (used in special applications)
• Bay current is connected to both zones during zone
interconnection if the bay was previously connected to
one of the two zones (typically used for feeder bays)
16
CntrlIncludes ). This
CntrlExcludes ). This option
The third option ensures that the feeder, which is out of
service, is not connected to any of the two zones during zone
interconnection.
Within the Bay function block it is decided by a parameter
setting whether this bay should be connected to the check
zone or not. In this way the end user has simple control over
the bays, which shall be connected to the overall check zone.
By appropriate configuration logic it is possible to take any
bay (that is, CT input) out of service. This can be done from
the local HMI or externally via binary signal. In that case all
internal current measuring functions (that is, differential
protection, sensitive differential protection, check zone,
breaker failure protection and overcurrent protection) are
disabled. At the same time, any trip command to this bay
circuit breaker can be inhibited.
Via two dedicated binary input signals it is possible to:
• Trip only the bay circuit breaker (used for integrated OC
protection tripping)
• Trip the whole differential zone to which this bay is
presently connected (used for backup-trip command
from either integrated or external bay circuit breaker
failure protection)
Finally dedicated trip binary output from the Bay function
block is available in order to provide common trip signal to
the bay circuit breaker from busbar differential protection,
breaker failure protection, backup overcurrent protection and
so on.
In this way the interface to the user is kept as simple as
possible and IED engineering work is quite straight forward.
Zone interconnection (Load transfer)
When this feature is activated the two integrated differential
protection zones are merged into one common, overall
differential zone. This feature is required in double busbar
stations when in any of the feeder bays both busbar
disconnectors are closed at the same time (that is, load
transfer). As explained in above section Bay each CT input
will then behave in the pre-set way in order to ensure proper
current balancing during this special condition. This feature
can be started automatically (when Zone Selection logic
determines that both busbar disconnectors in one feeder bay
are closed at the same time) or externally via dedicated binary
signal. If this feature is active for longer time than the pre-set
vale the alarm signal is given.
1MRK505273-BEN D
ABB