ABB RELION 670 Series Applications Manual page 105

1MRK 505 337-UUS A
Scheme1_RADSS "If not OPEN then CLOSED"
As the name of the scheme suggests, only when the auxiliary contacts signal clean open position
("normally open auxiliary (NO) contact input" = inactive and "normally closed auxiliary (NC) contact
input" = active), the disconnector is taken to be open. For all other signal combinations the
disconnector is considered to be closed. This scheme does not pose any special requirements to
the auxiliary contact timing. Only the disconnector NC contact must open before the disconnector
main contact is within arcing distance. The time during which the OPEN and CLOSED signal inputs
disagree (that is, both binary inputs are active or both are inactive) is monitored by the isolator
supervision function. The maximum time allowed before an alarm is given can be set according to
the disconnector timing.
Scheme2_INX "Closed or open if clear indication available otherwise last position saved"
As the name of the scheme suggests, only when the auxiliary contacts signal clean OPEN or clean
CLOSED position disconnector is considered to be open respectively closed. However this poses
the stringent requirements on the auxiliary contacts that the CLOSED signal must become active a
certain time (>150 ms) before current starts flowing for example, through arcing. Otherwise this
current will not be taken into account in the busbar protection and this can result in a
maloperation. Therefore, good timing of two auxiliary contacts is definitely required.
The time during which the OPEN and CLOSED signals disagree (that is, both binary inputs are
active or both are inactive) is monitored by the isolator supervision function for both of the above
two schemes. The maximum time allowed before an alarm is given can be set according to the
disconnector timing.
Table 12
Table 12:
Primary equipment
Normally
Open
auxiliary
contact
status
("closed" or
"a" contact)
open
open
closed
closed
Application manual
and the following two figures summarize the properties of these two schemes.
Treatment of primary object auxiliary contact status within BBP in REB670
Status in busbar
protection
Normally when
Closed "Scheme 1
auxiliary RADSS"
contact is selected
status
("open" or
"b" contact)
open closed
closed open
open closed
closed closed
Alarm facility
when Alarm after
"Scheme 2 settable
INX" time delay
is selected
Last yes
position
saved
open no
closed no
closed yes
Differential protection
Information visible
on local HMI
intermediate_00
open
closed
badState_11
Section 6
SEMOD127523-24 v2
SEMOD127523-27 v3
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