CHAPTER 8: THEORY OF OPERATION FAULT LOCATORC60 BREAKER PROTECTION SYSTEM – INSTRUCTION MANUAL 8-38The relay allows locating faults from delta-connected VTs. If the FAULT REPORT 1 VT SUBSTITUTION setting is set to “None,”and the VTs are connected in wye, the fault location is performed based on the actual phase to ground voltages. If the VTsare connected in delta, fault location is suspended.If the FAULT REPORT 1 VT SUBSTITUTION setting value is “V0” and the VTs are connected in a wye configuration, the faultlocation is performed based on the actual phase to ground voltages. If the VTs are connected in a delta configuration, faultlocation is performed based on the delta voltages and externally supplied neutral voltage:Eq. 8-13If the FAULT REPORT 1 VT SUBSTITUTION setting value is “I0” and the VTs are connected in a wye configuration, the faultlocation is performed based on the actual phase to ground voltages. If the VTs are connected in a delta configuration, faultlocation is performed based on the delta voltages and zero-sequence voltage approximated based on the zero-sequencecurrent:Eq. 8-14where ZSYS0 is the equivalent zero-sequence impedance behind the relay as entered under the fault report setting menu.V A13-- V N V AB V CA–+ =V B13-- V N V BC V AB–+ =V B13-- V N V CA V BC–+ =V A13-- V AB V CA– Z SYS0 I 0–=V B13-- V BC V AB– Z SYS0 I 0–=V B13-- V CA V BC– Z SYS0 I 0–=
