GE Multilin
G60 Generator Protection System
5-177
5 SETTINGS
5.6 GROUPED ELEMENTS
5
2.
CT saturation
The characteristic allows for very sensitive settings when fault current is low and less sensitive settings when fault current is
high and CT performance may produce incorrect operate signals.
•
STATOR DIFF LINE END SOURCE:
This setting selects the source connected to CTs in the end of the machine stator
winding closest to the load and furthest from the winding neutral point. Both line and neutral-side CTs should be wired
to measure their currents in the same direction with respect to the neutral point of the winding.
•
STATOR DIFF NEUTRAL END SOURCE:
This setting selects the source connected to CTs in the end of the machine
stator winding furthest from the load and closest to the winding neutral point. Both line and neutral-side CTs should be
wired to measure their currents in the same direction with respect to the neutral point of the winding.
•
STATOR DIFF PICKUP:
This setting defines the minimum differential current required for operation. This setting is
based on the amount of differential current that might be seen under normal operating conditions. A setting of 0.1 to
0.3 pu is generally recommended.
•
STATOR DIFF SLOPE 1:
This setting is applicable for restraint currents from zero to
STATOR DIFF BREAK 1
, and
defines the ratio of differential to restraint current above which the element will operate. This slope is set to ensure sen-
sitivity to internal faults at normal operating current levels. The criteria for setting this slope is to allow for maximum
expected CT mismatch error when operating at the maximum permitted current. This maximum error is generally in the
range of 5 to 10% of CT rating.
•
STATOR DIFF BREAK 1:
This setting defines the end of the Slope 1 region and the start of the transition region. It
should be set just above the maximum normal operating current level of the machine.
•
STATOR DIFF SLOPE 2:
This setting is applicable for restraint currents above the
STATOR DIFF BREAK 2
setting when
the element is applied to generator stator windings. This slope is set to ensure stability under heavy external fault con-
ditions that could lead to high differential currents as a result of CT saturation. A setting of 80 to 100% is recom-
mended. The transition region (as shown on the characteristic plot) is a cubic spline, automatically calculated by the
relay to result in a smooth transition between
STATOR DIFF SLOPE 1
and
STATOR DIFF SLOPE 2
with no discontinuities.
•
STATOR DIFF BREAK 2:
This setting defines the end of the transition region and the start of the Slope 2 region. It
should be set to the level at which any of the protection CTs are expected to begin to saturate.
Figure 5–81: STATOR DIFFERENTIAL SCHEME LOGIC
SETTING
SETTINGS
FLEXLOGIC OPERANDS
FLEXLOGIC OPERANDS
FLEXLOGIC OPERANDS
SETTING
SETTING
SETTING
STATOR DIFF
FUNCTION:
STATOR DIFF
SLOPE 2:
STATOR DIFF
BREAK 1:
STATOR DIFF
BREAK 2:
STATOR DIFF
SLOPE 1:
STATOR DIFF
PICKUP:
STATOR DIFF PKP A
STATOR DIFF PKP B
STATOR DIFF PKP C
STATOR DIFF DPO A
STATOR DIFF DPO B
STATOR DIFF DPO C
STATOR DIFF BLOCK:
Off = 0
Enabled = 1
STATOR DIFF
LINE END SOURCE:
STATOR DIFF
NEUTRAL END SOURCE:
IA
IA
IB
IB
IC
IC
RUN
RUN
RUN
Iad
Ibd
Icd
Iar
Ibr
Icr
830000A5.CDR
AND
Restraint Phasors
Differential Phasors
DC Offset
Removal
D.F.T.
and
Differential
and Restraint
Iar
Iad
Ibr
Ibd
Icr
Icd
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 ...