CHAPTER 10: THEORY OF OPERATION FAULT LOCATOR
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 10-61
10
If the FAULT REPORT 1 VT SUBSTITUTION setting value is “I0” and the VTs are connected in a wye configuration, the fault
location is performed based on the actual phase to ground voltages. If the VTs are connected in a delta configuration, fault
location is performed based on the delta voltages and zero-sequence voltage approximated based on the zero-sequence
current:
Eq. 10-84
where Z
SYS0
is the equivalent zero-sequence impedance behind the relay as entered under the fault report setting menu.
Figure 10-20: Fault locator scheme
Since the fault locator algorithm is based on the single-end measurement method, in three-terminal configuration
the estimation of fault location may not be correct at all three terminals especially if fault occurs behind the line's
tap respective to the given relay.
To Next Page
Loading...
