ABB Relion 670 Series Product Manual page 15

Busbar protection REB670
Customized
Product version: 1.2
these disconnectors then actually determine which CT input
(that is, bay) is connected to which differential protection
zone. For some more advanced features like end-fault or
blind-spot protection the actual status of the circuit breaker in
some or even all bays can be vital information for busbar
protection as well. The switch function block is used to take
the status of two auxiliary contacts from the primary device,
evaluate them and then to deliver the device primary contact
position to the rest of the zone selection logic.
For such applications typically two auxiliary contacts (that is,
normally open and normally closed auxiliary contacts) from
each relevant primary switching object shall be connected to
the IED. Then the status for every individual primary switching
object will be determined. The dedicated function block for
each primary switching object is available in order to
determine the status of the object primary contacts. By a
parameter setting one of the following two logical schemes
can be selected for each primary object individually by the
end user:
• If not open then closed (that is, as in RADSS schemes)
• Open or closed only when clearly indicated by aux
contact status (that is, as in INX schemes)
Table 1 gives quick overview about both schemes.
Table 1. Treatment of primary object auxiliary contact status
Primary equipment
Normally Open Normally
auxiliary Closed
contact status auxiliary
(that is, contact status
"closed" or (that is,
"a" contact) "open" or "b"
contact)
open open
open closed
closed open
closed closed
Bay
Each CT input is allocated to one dedicated bay function
block. This function block is used to provide complete user
interface for all signals from and towards this bay. It is also
used to influence bay measured current.
It is possible by a parameter setting
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
ABB
Status in busbar protection
when when
"Scheme 1 "Scheme 2
RADSS" INX"
is selected is selected
closed Last position
saved
open open
closed closed
closed closed
CTConnection to connect
Note that the first scheme only requires fast breaking normally
closed auxiliary contact (that is, b contact) for proper
operation. The timing of normally open auxiliary contact is not
critical because it is only used for supervision of the primary
object status. The second scheme in addition requires
properly timed-adjusted, early-making normally open auxiliary
contact (that is, early making a contact) for proper operation.
Regardless which scheme is used the time-delayed
disconnector/circuit breaker status supervision alarm is
available (that is, 00 or 11 auxiliary contact status). How two
integrated differential protection zones behave when
disconnector alarm appears is freely configurable by the end
user.
It is possible by a parameter setting to override the primary
object status as either permanently open or permanently
closed. This feature can be useful during testing, installation
and commissioning of the busbar protection scheme. At the
same time, separate alarm is given to indicate that the actual
object status is overwritten by a setting parameter.
It is to be noted that it is as well possible to use only normally
closed auxiliary contacts for Zone Selection logic. In that case
the Switch function blocks are not used.
Alarm facility
Alarm after Information visible on local HMI
settable time
delay
yes intermediate_00
no open
no closed
yes badState_11
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:
1MRK505273-BEN D
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