Toshiba GR200 Series Instruction Manual page 328

VT failure detection (VTF)
If a failure occurs on the secondary circuit in the voltage transformer (VT), the operation in
relays cannot be obtained properly because the relays do not measure voltages correctly.
Therefore, the VT failure detection (VTF) function is provided to block operating the relays
upon occurrence of the VT failure. Accordingly, if a VT failure is detected by the VTF function,
an alarm signal is issued for the relays upon occurrence of the VT failure. Accordingly, an
alarm signal is issued if a VT failure is detected by the VTF function; a detection signal by the
VTF function blocks operating the relay for the voltage monitor
After the disappearance of the VT failure, the VTF function can take account of the VT
secondary circuit being in healthy condition in the three-phase; the operation of the VTF
function is reset
the VTF alarm is automatically removed and then the user can find resetting the VTF alarm.
Note: The VTF function can block the operation in several relays, but it does not block
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the operation in other relays. To know the blocking, refer sections of the respective
protection functions.
Note: The user can programmable the operation using the setting and the PLC signals.
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Note: The implementation of particular features is dependent upon the selection of
hardware and the configuration of functions. Several IED models do not support certain
features. To determine whether a particular feature has been implemented within an IED,
identify the IED ordering number; and check the order number for the "G&T position" whilst
referring to the comparison table below. For more information, see
Table 2.21-1 Comparative table in respective ordering numbers
✓: Applicable
. Thus, the blocked relays are allowed to operate again. Incidentally, issuing
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Sec. Feature
– Main features
NA: Not applicable
Ordering No. at "G&T"
31 32
✓ ✓
- 307 -
6F2S1915 (0.46)
.
1
Appendix: Ordering
GRZ200 (Soft 031 & 032)
(2.62.0)
.