Signal Sources - GE L30 Instruction Manual

5.4 SYSTEM SETUP
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 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
frequency applications.
NOTE
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.
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 L30 algorithm (see
5
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

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.
5-92
setting determines which signal source is used (and hence which AC signal) for
is set to "Disabled" only in unusual circumstances; consult the factory for special variable-


SIGNAL SOURCES

SOURCE 1 NAME:
SRC 1
SOURCE 1 PHASE CT:
MESSAGE
None
SOURCE 1 GROUND CT:
MESSAGE
None
SOURCE 1 PHASE VT:
MESSAGE
None
SOURCE 1 AUX VT:
MESSAGE
None
L30 Line Current Differential System
V V ), while Clarke transformation of the
=
ANGLE REF A
(
V 2V V
= – –
FREQUENCY A B
setting to provide frequency tracking for
FREQUENCY TRACKING

SOURCE 1(2)
Range: up to six alphanumeric characters
Range: None, F1,... up to any 6 CTs. Only Phase CT
inputs are displayed.
Range: None, F1,... up to any 6 CTs. Only Ground CT
inputs are displayed.
Range: None, F5
Only phase voltage inputs are displayed.
Range: None, F5
Only auxiliary voltage inputs are displayed.
5 SETTINGS
) 3 ⁄
V ) for better performance dur-
C
FREQUENCY AND PHASE REFERENCE
5.4.3 SIGNAL SOURCES
GE Multilin