GE Multilin
G60 Generator Protection System
5-241
5 SETTINGS
5.6 GROUPED ELEMENTS
5
•
In addition the relay should be set properly with frequency tracking enabled and the source used as
FREQUENCY AND
PHASE REFERENCE
should be the one connected to generator terminal VTs. The tracking frequency, which is essen-
tially the generator frequency, will be used to block the sub-harmonic stator ground protection and auxiliary over volt-
age protection in the frequency range of 15 to 25 Hz.
b) 100% STATOR GROUND
PATH: SETTINGS
GROUPED ELEMENTS
SETTING GROUP 1(6)
STATOR GROUND
100% STATOR GROUND
The 100% stator ground function responds to third harmonic voltage measured at the generator neutral and output termi-
nals. When used in conjunction with the neutral overvoltage (fundamental frequency) element, it provides 100% ground
fault protection of the stator windings. Since the amount of third harmonic voltage that appears in the neutral is both load
and machine dependent, the protection method of choice is an adaptive method. The following formula is used to create an
adaptive operating quantity based on the amount of third harmonic that appears at the generator terminals.
(EQ 5.35)
where:
V
N(
3
rd)
is a magnitude of the 3rd harmonic in the voltage measured at the machine neutral point measured via an
auxiliary channel of the VT bank, and
V
0
(
3
rd)
is a magnitude of the 3rd harmonic in the zero-sequence voltage measured at the machine terminals.
This element requires wye-connected VTs for measurement of the third harmonic in the zero-sequence
voltage at the generator output terminals.
Example 1: Operating quantities under normal conditions.
Consider the figure shown below. In the case of a high impedance grounded machine, the neutral resistor is typically cho-
sen such that power dissipated in the resistor during a single line to ground fault is approximately equal to the reactive
power produced by the zero sequence capacitance of the stator winding and the GSU LV winding (
). At power system
frequencies, the neutral resistance is therefore equal to
, and at
, the neutral resistance is
.
For analysis, assume that
.
100% STATOR
GROUND
100% STATOR GROUND
FUNCTION: Disabled
Range: Disabled, Enabled
MESSAGE
100% STATOR GND STG1
PICKUP: 0.150 pu
Range: 0.000 to 0.900 pu in steps of 0.001
MESSAGE
100% STATOR GND STG1
DELAY: 1.00 s
Range: 0.00 to 600.00 s in steps of 0.01
MESSAGE
100% STATOR GND STG1
SUPV: 0.0057 pu
Range: 0.0010 to 0.1000 pu in steps of 0.0001
MESSAGE
100% STATOR GND STG2
PICKUP: 0.150 pu
Range: 0.000 to 0.900 pu in steps of 0.001
MESSAGE
100% STATOR GND STG2
DELAY: 0.00 s
Range: 0.00 to 600.00 s in steps of 0.01
MESSAGE
100% STATOR GND STG2
SUPV: 0.0045 pu
Range: 0.0010 to 0.1000 pu in steps of 0.0001
MESSAGE
100% STATOR GND BLK:
Off
Range: FlexLogic operand
MESSAGE
100% STATOR GROUND
TARGET: Self-reset
Range: Self-reset, Latched, Disabled
MESSAGE
100% STATOR GROUND
EVENTS: Disabled
Range: Disabled, Enabled
V
N
3
rd
(
)
V
N
3
rd
(
)
V
0 3
rd
(
)
+
---------------------------------------------
Pickup and
V
0 3
rd
(
)
V
N
3
rd
(
)
V
0 3
rd
(
)
+
---------------------------------------------
1 Pickup and
V
N
3
rd
(
)
V
0 3
rd
(
)
+
Supervision
>
–
>
<
NOTE
X
oc
X
oc
3
⁄
3
F
n
×
X
oc
E
3
10 V
=
,
R
5
Ω
, and
X
c
5
Ω
=
=
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 ...