GE Multilin
G60 Generator Protection System
9-9
9 APPLICATION OF SETTINGS
9.1 SETTING EXAMPLE
9
c) THIRD HARMONIC NEUTRAL UNDERVOLTAGE
If the phase VTs are delta connected then third harmonic voltage cannot be measured and the 100% stator ground element
cannot be used. In this case the third harmonic neutral undervoltage element can be used. Field measurements should be
taken over the entire operating range of the machine to determine the variation of the third harmonic voltage as shown
below:
Figure 9–3: THIRD HARMONIC NEUTRAL UNDERVOLTAGE FIELD MEASUREMENTS
The element is accurate for levels as low as 0.25 volts, secondary. In this case, the pickup setting will be:
(EQ 9.32)
The third harmonic will dip below the pickup setting between 95 and 105 megawatts. The element should be blocked over
this range. A margin of 5% should be added to the relay settings. The values for maximum and minimum power will be:
(EQ 9.33)
(EQ 9.34)
Voltage supervision will be given a setting of 0.8 pu in order to prevent maloperation during a sustained undervoltage con-
dition. A time delay of 5 seconds will be applied. If required, the element may be blocked when the machine is offline. Make
the following changes in EnerVista UR Setup or through the
SETTINGS
GROUPED ELEMENTS
SETTING GROUP 1
STATOR GROUND
3RD HARM NTRL UNDERVOLTAGE
menu:
83073
3
A1.CDR
Megawatts
Thir
d
harmonic
neutral
volt
age
PICKUP
0.25 V
240 V
-----------------
0.001 pu
=
=
Max Power
1.05
105 10
6
×
3 8000 157.5 66
×
×
×
---------------------------------------------------------
×
0.441 pu
=
=
Min Power
0.95
85 10
6
×
3 8000 157.5 66
×
×
×
---------------------------------------------------------
×
0.323 pu
=
=
Summary of Contents for Multilin g60
Page 10: ...x G60 Generator Protection System GE Multilin TABLE OF CONTENTS INDEX ...
Page 32: ...1 22 G60 Generator Protection System GE Multilin 1 5 USING THE RELAY 1 GETTING STARTED 1 ...
Page 160: ...4 30 G60 Generator Protection System GE Multilin 4 3 FACEPLATE INTERFACE 4 HUMAN INTERFACES 4 ...
Page 486: ...5 326 G60 Generator Protection System GE Multilin 5 10 TESTING 5 SETTINGS 5 ...
Page 518: ...6 32 G60 Generator Protection System GE Multilin 6 5 PRODUCT INFORMATION 6 ACTUAL VALUES 6 ...
Page 532: ...7 14 G60 Generator Protection System GE Multilin 7 2 TARGETS 7 COMMANDS AND TARGETS 7 ...
Page 748: ...D 10 G60 Generator Protection System GE Multilin D 1 IEC 60870 5 104 APPENDIX D D ...
Page 760: ...E 12 G60 Generator Protection System GE Multilin E 2 DNP POINT LISTS APPENDIX E E ...