Toshiba GR200 Series Instruction Manual page 56

Supervision of differential current (DIF-IdSV)
2.1.9
The differential current is monitored to check the health of the CT circuit by the differential
current supervision function (DIF-IdSV). The supervision function† detects the erroneous
differential current that appears in the case of a CT circuit failure. The supervision function is
available in all zones (DIFCH and DIFZA to DIFZF); it has a non-restraint current
characteristic. The supervising relay element is operated when On is set for scheme switch
[DIF-IdSV-EN].
PLC connection point "DIFSV_BLOCK" is provided when the user wishes to disable the
supervision function. To disable this function, the user can connect a signal to the
"DIFSV_BLOCK" using the PLC function. For more information about the supervision
function, see Chapter
Supervision of differential current
(i)
In order to detect an erroneous differential current in the DIF function, supervising elements
are provided for the check zone (DIFSVCH) and discriminating zones A to D (DIFSVZA to
DIFSVZF). The user can set an operating value for these supervision elements using the
setting [DIF-IdSV].
Blocking of DIF operation
(ii)
If the supervising element detects an erroneous differential current, a DIF trip command can
be blocked (either for all zones or individually for each protection zone).
To block the differential trip, the user can select the mode for blocking using scheme
switch [DIF-IdSVBlk]. When Block-PZ is set, and an erroneous differential current occurs, the
DIF trip command will be blocked for the respective protection zones. When Block-AZ is set,
the DIF trip command is blocked for all protection zones. Table 2.1-6 summarizes the settings
in the DIF-IdSV function.
Setting items Mode / range
10 – 20,000A
DIF-IdSV
0 – 300s
TDIF-IdSV
DIF-IdSV-EN
Block-PZ
DIF-IdSVBlk
Block-AZ
Automatic supervision function.
Table 2.1-6 DIF-IdSV setting
Unit
A Operating value of DIF relay for Id-SV
s Detection time for Id-SV
Off Disenabling the monitor
–
On Enabling the monitor
Non Operation not blocked by IdSV
– Operation blocked in error zones
Operation blocked in all zones
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6F2S1931 (0.20)
Contents
Centralized GRB200
(Soft: 030, 031, 032, 033, 034)
Defau
lt
200
10
Off
Non