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Directional earth fault command protection (DEFCAR)
Directional earth fault command protection (DEFCAR) provides POP, UOP and BOP
techniques† using two elements of earth fault protection between in forward and in reverse
(DEFCF and DEFCR‡). POP, UOP and BOP can issue either a single-pole trip (1P) or three-
phase trip (3P). These can also enable to run the function of autoreclose (ARC). User can select
either first tripping or delayed tripping in DEFCAR with set of delay timer. Thus, it is possible
to give priority to the function of distance carrier protection (DISCAR) so that DISCAR runs
faster than DEFCAR. DEFCAR send a trip block signal for the opposite terminal when one or
two poles in CB are open and when the failure of voltage transformer occurs.
†Note: When both DISCAR and DEFCAR are used mutually for the command protection,
user should coordinate the technique between DISCAR and DEFCAR. For the
selection of the techniques in DEFCAR, see section 2.12.
‡Note: In DEFCAR, EF1 is used for a forward element (DEFCF); EF2 is used for a
reverse element (DEFCR). Both EF1 and EF2 are the function of earth fault
protection (EF). For more information, see Chapter
Relay application: Earth fault
protection
.
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Note: Several IED models do not have carrier features. To determine whether the features
are implemented in the IED or not, locate the IED ordering number; and check the order
number at “G&T position” referring to the comparison table below. For more information, see
Appendix: Ordering
.
Table 2.13-1 Comparative table in respective ordering numbers
Directional-earth-fault carrier command protection
✓: Applicable NA: Not applicable
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