Toshiba GR200 Series Instruction Manual page 55

Scheme for blocking DIF operation
(v)
If a failure (open-circuit) in the CT is detected, the trip command shall be blocked; the logic for
the generation of no-block signals is also shown in Figure 2.1-16. When no failures are detected
in the CT circuit, the trip command is un-blocked by the signals CTFCH-NO-BLK or CTFZA-
NO-BLK to CTFZF-NO-BLK for the respective zones.
The user can select a mode for blocking using scheme switch [DIF-CTFBlk]. When Block-
PZ is set, and a failure occurs in the CT circuit, the DIF trip command will be blocked for the
respective protection zones. On the other hand, when Block-AZ is set, the DIF trip command
is blocked for all protection zones. The user should note that the DIF trip command is not
blocked when Non is set. The settings and scheme switches for the CT circuit failure detection
function are summarized in Table 2.1-5.
Setting items Mode / range
CTF-EN
OPT-On
20 – 5000
DIF-CTF 2
UV-CTF 2
5.0 – 130.0
UVD-CTF 2
Block-PZ
DIF-CTFBlk
Block-AZ
Note: The logic for zone B to zone F is similar to zone A.
1
Note: The user must set the value of current in terms of the primary current in the CT
2
circuit. However, the user should set voltage values in terms of the secondary
voltage of the VT circuit.
Table 2.1-5 CTF setting switch
Unit
CTF operation is disabled.
–
Off
CTF operation enabled. If a CTF
condition is detected it will not reset
even if under-voltage element-CTF
–
On
(UVCTF) or under-voltage-differential
element-CTF (UVDCTF) have operated
CTF operation enabled. Following CTF
detection, the CTF function will reset if
–
the UVCTF or UVDCTF elements have
operated.
DIF relay for CTF detection; operating
A
value user setting.
UV relay for CTF blocking; operating
V
value user setting.
UVD relay for CTF blocking; operating
1 – 20 V
value user setting.
DIF trip is not blocked
–
Non
DIF trip is blocked for respective DIFZA
–
to DIFZF
DIF trip is blocked for DIFCH and
–
DIFZA to DIFZF
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6F2S1931 (0.20)
Contents
Centralized GRB200
(Soft: 030, 031, 032, 033, 034)
Default
Off
200
46.0
5
Non