Signal Sources - GE L90 Instruction Manual

5 SETTINGS
The phase sequence of the power system is required to properly calculate sequence components and power parameters.
The setting matches the power system phase sequence. Note that this setting informs the relay of the
PHASE ROTATION
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
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 (
phase signals is used for frequency metering and tracking (
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. These results in very precise correlation of time tagging in the event recorder between
different UR-series relays provided the relays have an IRIG-B connection.
FREQUENCY TRACKING
cial variable-frequency applications.
NOTE
The nominal system frequency should be selected as 50 Hz or 60 Hz only. The
setting, used as a reference for calculating all angles, must be identical for all terminals. Whenever the 87L function
NOTE
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
all other elements and functions.
!"
PATH: SETTINGS SYSTEM SETUP
# SOURCE 1
#
MESSAGE
MESSAGE
MESSAGE
MESSAGE
Four identical source menus are available. The "SRC 1" text can be replaced by with a user-defined name appropriate for
the associated source.
"F" and "L" represent the module slot position. The number directly following these letters represents 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.
It is possible to select the sum of up to five (5) CTs. The first channel displayed is the CT to which all others will be referred.
For example, the selection "F1+F5" indicates the sum of each phase from channels "F1" and "F5", scaled to whichever CT
has the higher ratio. Selecting "None" hides the associated actual values.
GE Multilin
setting determines which signal source is used (and hence which AC signal) for
V
should only be set to "Disabled" in very unusual circumstances; consult the factory for spe-
FREQUENCY TRACKING
!" !

SIGNAL SOURCES

SOURCE 1(4)
SOURCE 1 NAME:
SRC 1
SOURCE 1 PHASE CT:
None
SOURCE 1 GROUND CT:
None
SOURCE 1 PHASE VT:
None
SOURCE 1 AUX VT:
None
L90 Line Differential Relay
V V ), while Clarke transformation of the
=
ANGLE REF A
(
2V V V
= – –
FREQUENCY A B C
FREQUENCY AND PHASE REFERENCE
setting to provide frequency tracking for
Range: up to 6 alphanumeric characters
Range: None, F1, F5, F1+F5,... up to a combination of
any 5 CTs. Only Phase CT inputs are displayed.
Range: None, F1, F5, F1+F5,... up to a combination of
any 5 CTs. Only Ground CT inputs are displayed.
Range: None, F1, F5, L1, L5
Only phase voltage inputs will be displayed.
Range: None, F1, F5, L1, L5
Only auxiliary voltage inputs will be displayed.
5.3 SYSTEM SETUP
) 3 ⁄
) for better performance dur-
5.3.3 SIGNAL SOURCES
5-37
5