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5 SETTINGS
The power system
NOMINAL FREQUENCY
cannot be measured from available signals. This may 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
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
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.
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.
GE Multilin
value is used as a default to set the digital sampling rate if the system frequency
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(2)
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
F60 Feeder Protection System
V
=
V
), while Clarke transformation of the
ANGLE REF
A
(
=
2V
–
V
–
V
FREQUENCY
A
B
C
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
Only phase voltage inputs will be displayed.
Range: None, F1, F5
Only auxiliary voltage inputs will be displayed.
5.3 SYSTEM SETUP
) 3 ⁄
) for better performance dur-
5.3.3 SIGNAL SOURCES
5-67
5
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