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Miscellaneous functions
2.1.6
Trip mode
(i)
Every OC element has a selectable tripping mode; the mode is selected using a scheme switch.
For the OC1 element, for example, a scheme switch [OC1-OPMD] is provided. When a trip is
required for any faults that are detected, 3POR (a fault occurs in one or more phases) is set for
the scheme switch [OC1-OPMD]. Conversely, when a trip is only required for faults that occur
in two or more phases, 2OUTOF3 (a fault occurs in two or more phases) is set for the scheme
switch [OC1-OPMD].
Phase-A
X
–
–
X
–
X
X
Note: A tick (
A mark (X) indicates the occurrence of a fault on a particular phase. A mark
shown thus (–) indicates that no fault has occurred on that particular phase.
Blocking OC by ICD
(ii)
The operation of each OC element can be blocked if the ICD function detects a second harmonic
current caused by the magnetizing inrush current phenomenon when a transformer is
energized. For example, for the OC1 element, the scheme switch [OC1-2fBlk] is provided, and
Block-AllP should be set when the user wishes to block all three-phases of the OC1 element
when the second harmonic associated with the magnetizing inrush current is present.
Alternatively, Block-PerP is set if blocking is just required for a single phase concerting to the
phenomenon. Non is set for the scheme switch [OC1-2fBlk] as the default setting. For more
information about the ICD function, see Chapter 2.10.
Blocking OC by VTF
(iii)
The operation of the OC element can be blocked by the voltage transformer failure (VTF)
function via a scheme switch. For example, Block can be set for the scheme switch [OC1-
VTFBlk] to block the operation of the OC1 element during a VTF condition. Non is set for the
scheme switch [OC1-VTFBlk] as a default. For more information about the VTF, see Chapter
2.20.
OC operation for auto-reclose
(iv)
The OC element activates the auto-reclose (ARC) function. However, if for example ARC is not
Table 2.1-6 Fault type and tripping mode
Fault type
Phase-B
Phase-C
–
X
–
X
X
–
X
✓
) indicates that a trip is issued when faults are detected.
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Setting [OC1-OPMD]
3POR
–
✓
–
✓
X
✓
–
✓
X
✓
X
✓
X
✓
6F2T0207 (0.01)
2OUTOF3
No trip
No trip
No trip
✓
✓
✓
✓
GRE200 (5,6)
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