GE L30 User Manual

5-92 L30 Line Current Differential System GE Multilin
5.4 SYSTEM SETUP 5 SETTINGS
5
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 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 the factory for special variable-
frequency applications.
The frequency tracking feature functions only when the L30 is in the “Programmed” mode. If the L30 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 L30 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(2)
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. See the Introduction to AC Sources section at the beginning of this chapter for details on this
concept.
It is possible to select the sum of all CT combinations. 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.
 SOURCE 1

SOURCE 1 NAME:
SRC 1
Range: up to six alphanumeric characters
MESSAGE
SOURCE 1 PHASE CT:
None
Range: None, F1,... up to any 6 CTs. Only Phase CT
inputs are displayed.
MESSAGE
SOURCE 1 GROUND CT:
None
Range: None, F1,... up to any 6 CTs. Only Ground CT
inputs are displayed.
MESSAGE
SOURCE 1 PHASE VT:
None
Range: None, F5
Only phase voltage inputs are displayed.
MESSAGE
SOURCE 1 AUX VT:
None
Range: None, F5
Only auxiliary voltage inputs are displayed.
V
ANGLE REF
V
A
=
V
FREQUENCY
2V
A
V
B
– V
C
–()3⁄=
NOTE
NOTE
NOTE

GE L30 Specifications

General

Brand	GE
Model	L30
Category	Relays
Language	English