48MHz and 16MB 3BSE066495R1

48MHz and 16MB 3BSE066495R1

48MHz and 16MB 3BSE066495R1

An example will be given, how sensitive-earth-fault protection for power lines can be achieved by using negative-sequence directional overcurrent protection elements within a CVGAPC function.

This functionality can be achieved by using one CVGAPC function.

The following shall be done to ensure proper operation of the function:

1. Connect three-phase power line currents and three-phase power line voltages to one CVGAPC instance (for example, GF04)

2. Set CurrentInput to NegSeq (please note that CVGAPC function measures I2 current and NOT 3I2 current; this is essential for proper OC pickup level setting)

3. Set VoltageInput to -NegSeq (please note that the negative sequence voltage phasor is intentionally inverted in order to simplify directionality

4. Set base current IBase value equal to the rated primary current of power line CTs

5. Set base voltage UBase value equal to the rated power line phase-to-phase voltage in kV

6. Set RCADir to value +65 degrees (NegSeq current typically lags the inverted NegSeq voltage for this angle during the fault)

7. Set ROADir to value 90 degree

8. Set LowVolt_VM to value 2% (NegSeq voltage level above which the directional element will be enabled)

9. Enable one overcurrent stage (for example, OC1)

10. By parameter CurveType_OC1 select appropriate TOC/IDMT or definite time delayed curve in accordance with your network protection philosophy 11. Set StartCurr_OC1 to value between 3-10% (typical values)

12. Set tDef_OC1 or parameter “k” when TOC/IDMT curves are used to insure proper time coordination with other earth-fault protections installed in the vicinity of this power line

13. Set DirMode_OC1 to Forward

14. Set DirPrinc_OC1 to IcosPhi&U

15. Set ActLowVolt1_VM to Block