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5.4 SYSTEM SETUP
User selection of AC parameters for comparator elements:
CT/VT modules automatically calculate all current and voltage parameters from the available inputs. Users must select the
specific input parameters to be measured by every element in the relevant settings menu. The internal design of the ele-
ment specifies which type of parameter to use and provides a setting for source selection. In elements where the parameter
may be either fundamental or RMS magnitude, such as phase time overcurrent, two settings are provided. One setting
specifies the source, the second setting selects between fundamental phasor and RMS.
AC input actual values:
The calculated parameters associated with the configured voltage and current inputs are displayed in the current and volt-
age sections of actual values. Only the phasor quantities associated with the actual AC physical input channels will be dis-
played here. All parameters contained within a configured source are displayed in the sources section of the actual values.
DISTURBANCE DETECTORS (INTERNAL):
The disturbance detector (ANSI 50DD) element is a sensitive current disturbance detector that detects any disturbance on
the protected system. The 50DD function is used directly in some elements in the relay, for example VT Fuse Failure detec-
tor or Fault Report. It can also be used to supervise current-based elements to prevent maloperation as a result of the
wrong settings or external CT wiring problem. A disturbance detector is provided for each source.
The 50DD function responds to the changes in magnitude of the sequence currents. The disturbance detector scheme
logic is as follows:
5
The disturbance detector responds to the change in currents of twice the current cut-off level. The default cut-off threshold
is 0.02 pu; thus by default the disturbance detector responds to a change of 0.04 pu. The metering sensitivity setting (
UCT SETUP
DISPLAY PROPERTIES
accordingly.
EXAMPLE USE OF SOURCES:
An example of the use of sources is shown in the diagram below. A relay could have the following hardware configuration:
5-84
ACTUAL
SOURCE 1
CURRENT PHASOR
_1
_2
_0
ACTUAL
SOURCE 2
CURRENT PHASOR
_1
_2
_0
ACTUAL
SOURCE 6
CURRENT PHASOR
_1
_2
_0
Figure 5–21: DISTURBANCE DETECTOR LOGIC DIAGRAM
CURRENT CUT-OFF LEVEL
D30 Line Distance Protection System
SETTING
PRODUCT SETUP/DISPLAY
PROPERTIES/CURRENT
CUT-OFF LEVEL
FLEXLOGIC OPERAND
_1 -
_1' >2*CUT-OFF
_2 -
_2' >2*CUT-OFF
OR
SRC 1 50DD OP
_0 -
_0' >2*CUT-OFF
Where ' is 2 cycles old
SETTING
PRODUCT SETUP/DISPLAY
PROPERTIES/CURRENT
CUT-OFF LEVEL
FLEXLOGIC OPERAND
_1 -
_1' >2*CUT-OFF
SRC 2 50DD OP
_2 -
_2' >2*CUT-OFF
OR
_0 -
_0' >2*CUT-OFF
Where ' is 2 cycles old
SETTING
PRODUCT SETUP/DISPLAY
PROPERTIES/CURRENT
CUT-OFF LEVEL
FLEXLOGIC OPERAND
_1 -
_1' >2*CUT-OFF
_2 -
_2' >2*CUT-OFF
OR
SRC 6 50DD OP
_0 -
_0' >2*CUT-OFF
Where ' is 2 cycles old
) controls the sensitivity of the disturbance detector
5 SETTINGS
827092A3.CDR
PROD-
GE Multilin
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