GE L60 Instruction Manual page 213

5 SETTINGS
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:
ACTUAL
SOURCE 1
CURRENT PHASOR
_1
_2
_0
ACTUAL
SOURCE 2
CURRENT PHASOR
_1
_2
_0
ACTUAL
SOURCE 6
CURRENT PHASOR
_1
_2
_0
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:
This configuration could be used on a two-winding transformer, with one winding connected into a breaker-and-a-half sys-
tem. The following figure shows the arrangement of sources used to provide the functions required in this application, and
the CT/VT inputs that are used to provide the data.
GE Multilin
SETTING
PRODUCT SETUP/DISPLAY
PROPERTIES/CURRENT
CUT-OFF LEVEL
Where ' is 2 cycles old
SETTING
PRODUCT SETUP/DISPLAY
PROPERTIES/CURRENT
CUT-OFF LEVEL
Where ' is 2 cycles old
SETTING
PRODUCT SETUP/DISPLAY
PROPERTIES/CURRENT
CUT-OFF LEVEL
Where ' is 2 cycles old
Figure 5–20: DISTURBANCE DETECTOR LOGIC DIAGRAM

CURRENT CUT-OFF LEVEL
L60 Line Phase Comparison System
FLEXLOGIC OPERAND
_1 - _1' >2*CUT-OFF
_2 - _2' >2*CUT-OFF
OR SRC 1 50DD OP
_0 - _0' >2*CUT-OFF
FLEXLOGIC OPERAND
_1 - _1' >2*CUT-OFF
SRC 2 50DD OP
_2 - _2' >2*CUT-OFF
OR
_0 - _0' >2*CUT-OFF
FLEXLOGIC OPERAND
_1 - _1' >2*CUT-OFF
_2 - _2' >2*CUT-OFF
OR SRC 6 50DD OP
_0 - _0' >2*CUT-OFF
) controls the sensitivity of the disturbance detector
5.3 SYSTEM SETUP
827092A3.CDR
PROD-
5-85
5