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 frequency tracking feature will function only when the L90 is in the "Programmed" mode. If the L90 is "Not Pro-
grammed", then metering values will be available but may exhibit significant errors.
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
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.
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-

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 Current Differential System
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
FREQUENCY TRACKING
Range: up to six alphanumeric characters
Range: None, F1, F5, F1+F5,... up to a combination of
any 6 CTs. Only Phase CT inputs are displayed.
Range: None, F1, F5, F1+F5,... up to a combination of
any 6 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.
5.4 SYSTEM SETUP
) 3 ⁄
) for better performance dur-
5.4.3 SIGNAL SOURCES
5-61
5