ABB RET670 Applications Manual page 569

1MRK504116-UUS C
Application manual
7. Select CurveType_OC1 to value ANSI Very inv
8. If required set minimum operating time for this curve by using parameter
tMin_OC1 (default value 0.05s)
9. Set PickupCurr_OC1 to value 185%
10. Set VCntrlMode_OC1 to On
11. Set VDepMode_OC1 to Slope
12. Set VDepFact_OC1 to value 0.25
13. Set VHighLimit_OC1 to value 100%
14. Set VLowLimit_OC1 to value 25%
Proper operation of the CVGAPC function made in this way can easily be verified by
secondary injection. All other settings can be left at the default values. Furthermore the
other built-in protection elements can be used for other protection and alarming purposes.
Loss of excitation protection for a generator
Example will be given how by using positive sequence directional overcurrent
protection element within a CVGAPC function, loss of excitation protection for a
generator can be achieved. Let us assume that from rated generator data the following
values are calculated:
• Maximum generator capability to contentiously absorb reactive power at zero
active loading 38% of the generator MVA rating
• Generator pull-out angle 84 degrees
This functionality can be achieved by using one CVGAPC function. The following
shall be done in order to insure proper operation of the function:
1. Connect three-phase generator currents and three-phase generator voltages to one
CVGAPC instance (for example, GF02)
2. Set parameter CurrentInput to PosSeq
3. Set parameter VoltageInput to PosSeq
4. Set base current value to the rated generator current primary amperes
5. Set base voltage value to the rated generator phase-to-phase voltage in kV
6. Set parameter RCADir to value -84 degree (that is, current lead voltage for this angle)
7. Set parameter ROADir to value 90 degree
8. Set parameter LowVolt_VM to value 5%
9. Enable one overcurrent step (for example, OC1)
10. Select parameter CurveType_OC1 to value IEC Def. Time
11. Set parameter PickupCurr_OC1 to value 38%
12. Set parameter tDef_OC1 to value 2.0s (typical setting)
13. Set parameter DirMode_OC1 to Forward
14. Set parameter DirPrinc_OC1 to IcosPhi&V
15. Set parameter ActLowVolt1_VM to Block
Section 3
IED application
563