12. Set
VDepFact_OC1
to value 0.25
13. Set
UHighLimit_OC1
to value 100%
14. Set
ULowLimit_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.
6.1.3.6
Loss of excitation protection for a generator
M13088-182 v3
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
StartCurr_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&U
15. Set parameter
ActLowVolt1_VM
to
Block
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. However
it shall be noted that set values for RCA & ROA angles will be applicable for OC2
step if directional feature is enabled for this step as well. Figure
protection characteristic
1MRK 511 423-UEN A
Section 6
Multipurpose protection
Bay control REC650 2.2 IEC
87
Application manual
