ABB REB670 Applications Manual page 129

1MRK 505 337-UUS -
Application manual
Diff Oper Level
Sensitive Oper Level
IEC06000142 V1 EN
Figure 50: Differential protection operation characteristic
Additionally the sensitive differential protection can be time delayed and it must be
externally enabled by a binary signal (that is, from external open delta VT overvoltage
relay or power transformer neutral point overcurrent relay).
The setting parameters for the check zone are set via the local HMI or PCM600.
Such check zone is included in the IED. By a parameter setting CheckZoneSel =
NotConnected/Connected can be decided, individually for every bay, if it shall be
connected to the check zone or not. This setting is available in bay function block.
For every zone there is a setting parameter CheckZoneSup, which can be set to Enabled or
Disabled. This setting parameter determines if the individual zone shall be supervised or
not by a check zone. This setting is available in both Zone functions. Finally the check
zone shall be enabled (that is, setting parameter Operation shall be set to Enabled) in order
to fully enable the check zone. Operating characteristics for the check zone can be set
independently from the two discriminating zones.
However, it is to be observed that the check zone has slightly different operating
characteristic from the usual discriminating zones. For the check zone the resultant
outgoing current is used as stabilizing current instead of total incoming current in order to
guarantee the check zone operation for all possible operating conditions in the station. The
check zone operating characteristic is shown in figure 51:
Sensitive
differential
protection
Operate
region
Sens Iin Block
s=0.53
Section 6
Differential protection
Differential protection
operation characteristic
I [Primary Amps]
in
en06000142.vsd
123