ABB Relion 670 Series Technical Reference Manual page 139

1MRK 505 208-UEN B
Technical reference manual
In order to guarantee proper operation of the IED, the first instance
of Bay function block must always be used in the configuration.
It is possible by a parameter setting CTConnection to connect or disconnect the CT
input to the bay function block. Once the CT input is connected to the bay function
block this associated current input can be included to or excluded from the two
internally available differential functions in software. This can be done by a
parameter setting for simple station layouts (that is, one-and-a-half breaker
stations) or alternatively via dedicated logical scheme (that is, double busbar
stations). For each bay the end user have to select one of the following five
alternatives:
• 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, CntrlIncludes). This 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, CntrlExcludes). This option 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:
Section 5
Differential protection
133