Toshiba GR200 Series - 2.21.4 Miscellaneous functions; (i) OV operation blocked by the occurrence of VT failure; (ii) OV trip signal; (iii) Execution of OV function

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 305 -
Figure 2.21-3 Faults occurrences and reset operation when IDMT being applied
2.21.4 Miscellaneous functions
(i) OV operation blocked by the occurrence of VT failure
Blocking the OV function may be required when a failure in the voltage transformer occurs. In
this case, the user shall set Block for scheme switch [OV1-VTFBlk]. Non (as a default) is set
for scheme switch [OV1-VTFBlk] in order that the OV function is not blocked by the failure.
(ii) OV trip signal
The OV function issues a trip command for the trip circuit (TRC†) when Trip is set for scheme
switch [OV1-UseFor] as the normal trip operation. However, when an alarm signal in place of
the trip command is required, the user can set Alarm for the scheme switch [OV1-UseFor].
†Note: For more information about the trip circuit, see Chapter Relay application: Trip
circuit .
(iii) Execution of OV function
Set On for scheme switch [OV1-EN]. Otherwise, set Off for the scheme switch [OV1-EN] if the
OV1 element is not required to operate.
2.21.5 Scheme logic
Figure 2.21-4 shows the OV1 logic. Signal connection points “OV1_BLOCK” are provided for
the block of the operation of the OV1 element. For testing, the OV1-PU element is provided; it
Condition fault occurrence
Fault observation by the relay
Issue of trip command
Trip level
Incrimination of time counter
corresponding to the fault
duration.
T
1
T
1
: Resetting time set by the user
T
2
: Actual resetting time in the relay operation
T
3
: Time gap between fault occurrence and relay start time
Tripping
T
1
T
1
T
1
T
2
T
2
T
3
Intermittent fault
Series faults
Relay operation reset
Reset of time counter
Increment process in time
counter
Value maintenance of time counter