CHAPTER 5: SETTINGS
SYSTEM SETUP
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
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5
The power system
NOMINAL FREQUENCY
value is used as a default to set the digital sampling rate if the system frequency
cannot be measured from available signals. This can happen if the signals are not present or are heavily distorted. Before
reverting to the nominal frequency, the frequency tracking algorithm holds the last valid frequency measurement for a
safe period of time while waiting for the signals to reappear or for the distortions to decay.
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 and informs the relay of the actual system phase
sequence, either ABC or ACB. CT and VT inputs on the relay, labelled as A, B, and C, must be connected 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 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 (V
ANGLE REF
= V
A
), while Clarke transformation of the phase
signals is used for frequency metering and tracking (V
FREQUENCY
= (2V
A
- V
B
- V
C
) / 3) for better performance during 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 always displays zero degrees and all other phase angles are relative to this signal. 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 GE Grid Solutions for special variable-
frequency applications.
5.5.3 Signal sources
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 frequency tracking feature functions only when the L90 is in the “Programmed” mode. If the L90 is “Not
Programmed,” then metering values are available but can exhibit significant errors.
Select the nominal system frequency 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 UR algorithm. Whenever the 87L
function is “Disabled,” the frequency tracking mechanism reverts to the UR-series mechanism that uses the
FREQUENCY TRACKING
setting to provide frequency tracking for all other elements and functions.
SOURCE 1
SOURCE 1 NAME:
SRC 1
Range: up to 20 alphanumeric characters
SOURCE 1 PHASE CT:
None
Range: None, F1,... up to any 6 CTs. Only Phase CT
inputs are displayed.
SOURCE 1 GROUND CT:
None
Range: None, F1,... up to any 6 CTs. Only Ground CT
inputs are displayed.
SOURCE 1 PHASE VT:
None
Range: None, F5, L5
Only phase voltage inputs are displayed
SOURCE 1 AUX VT:
None
Range: None, F5, L5
Only auxiliary voltage inputs are displayed
Содержание L90
Страница 14: ...1 4 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FOR FURTHER ASSISTANCE CHAPTER 1 INTRODUCTION 1 ...
Страница 68: ...2 54 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL SPECIFICATIONS CHAPTER 2 PRODUCT DESCRIPTION 2 ...
Страница 136: ...3 68 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL CONNECT TO D400 GATEWAY CHAPTER 3 INSTALLATION 3 ...
Страница 224: ...4 88 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FLEXLOGIC DESIGN USING ENGINEER CHAPTER 4 INTERFACES 4 ...
Страница 692: ...6 36 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL PRODUCT INFORMATION CHAPTER 6 ACTUAL VALUES 6 ...
Страница 708: ...7 16 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TARGETS MENU CHAPTER 7 COMMANDS AND TARGETS 7 ...
Страница 742: ...9 6 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 9 COMMISSIONING 9 ...
Страница 804: ...10 62 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FAULT LOCATOR CHAPTER 10 THEORY OF OPERATION 10 ...
Страница 872: ...C 6 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL COMMAND LINE INTERFACE APPENDIX C COMMAND LINE INTERFACE C ...
Страница 878: ...D 6 L90 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL REVISION HISTORY APPENDIX D MISCELLANEOUS D ...
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