GE Multilin
L90 Line Current Differential System
5-81
5 SETTINGS
5.4 SYSTEM SETUP
5
The phase sequence of the power system is required to properly calculate sequence components and power parameters.
The
PHASE ROTATION
setting matches the power system phase sequence. Note that this setting informs the relay of the
actual system phase sequence, either ABC or ACB. CT and VT inputs on the relay, labeled as A, B, and C, must be con-
nected to system phases A, B, and C for correct operation.
The
FREQUENCY AND PHASE REFERENCE
setting determines which signal source is used (and hence which AC signal) for
phase angle reference. The AC signal used is prioritized based on the AC inputs that are configured for the signal source:
phase voltages takes precedence, followed by auxiliary voltage, then phase currents, and finally ground current.
For three phase selection, phase A is used for angle referencing (
), while Clarke transformation of the
phase signals is used for frequency metering and tracking (
) for better performance dur-
ing fault, open pole, and VT and CT fail conditions.
The phase reference and frequency tracking AC signals are selected based upon the Source configuration, regardless of
whether or not a particular signal is actually applied to the relay.
Phase angle of the reference signal will always display zero degrees and all other phase angles will be relative to this sig-
nal. If the pre-selected reference signal is not measurable at a given time, the phase angles are not referenced.
The phase angle referencing is done via a phase locked loop, which can synchronize independent UR-series relays if they
have the same AC signal reference. This results in very precise correlation of phase angle indications between different
UR-series relays.
FREQUENCY TRACKING
is set to
“
Disabled
”
only in unusual circumstances; consult the factory for special variable-
frequency applications.
The frequency tracking feature functions only when the L90 is in the “Programmed” mode. If the L90 is “Not Pro-
grammed”, then metering values are available but can exhibit significant errors.
The nominal system frequency should be selected as 50 Hz or 60 Hz only. The
FREQUENCY AND PHASE REFERENCE
setting, used as a reference for calculating all angles, must be identical for all terminals. Whenever the 87L function
is “Enabled”, the frequency tracking function is disabled, and frequency tracking is driven by the L90 algorithm (see
the
Theory of operation
chapter). Whenever the 87L function is “Disabled”, the frequency tracking mechanism
reverts to the UR-series mechanism which uses the
FREQUENCY TRACKING
setting to provide frequency tracking for
all other elements and functions.
5.4.3 SIGNAL SOURCES
PATH: SETTINGS
SYSTEM SETUP
SIGNAL SOURCES
SOURCE 1(4)
Identical menus are available for each source. The "SRC 1" text can be replaced by with a user-defined name appropriate
for the associated source.
The first letter in the source identifier represents the module slot position. The number directly following this letter repre-
sents either the first bank of four channels (1, 2, 3, 4) called “1” or the second bank of four channels (5, 6, 7, 8) called “5” in
a particular CT/VT module. Refer to the
Introduction to AC sources
section at the beginning of this chapter for additional
details on this concept.
SOURCE 1
SOURCE 1 NAME:
SRC 1
Range: up to six alphanumeric characters
MESSAGE
SOURCE 1 PHASE CT:
None
Range: None, F1, F5, F1+F5,... up to a combination of
any 6 CTs. Only Phase CT inputs are displayed.
MESSAGE
SOURCE 1 GROUND CT:
None
Range: None, F1, F5, F1+F5,... up to a combination of
any 6 CTs. Only Ground CT inputs are displayed.
MESSAGE
SOURCE 1 PHASE VT:
None
Range: None, F5, L5
Only phase voltage inputs will be displayed.
MESSAGE
SOURCE 1 AUX VT:
None
Range: None, F5, L5
Only auxiliary voltage inputs will be displayed.
V
ANGLE REF
V
A
=
V
FREQUENCY
2
V
A
V
B
–
V
C
–
3
=
NOTE
NOTE
NOTE
Summary of Contents for UR Series L90
Page 652: ...A 16 L90 Line Current Differential System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 772: ...B 120 L90 Line Current Differential System GE Multilin B 4 MEMORY MAPPING APPENDIX B B ...
Page 802: ...C 30 L90 Line Current Differential System GE Multilin C 7 LOGICAL NODES APPENDIX C C ...
Page 812: ...D 10 L90 Line Current Differential System GE Multilin D 1 IEC 60870 5 104 APPENDIX D D ...
Page 824: ...E 12 L90 Line Current Differential System GE Multilin E 2 DNP POINT LISTS APPENDIX E E ...
Page 834: ...F 10 L90 Line Current Differential System GE Multilin F 3 WARRANTY APPENDIX F F ...
Page 846: ...xii L90 Line Current Differential System GE Multilin INDEX ...
