Supervising Elements - GE L90 Instruction Manual

5.5 GROUPED ELEMENTS
a) MAIN MENU
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PATH: SETTINGS GROUPED ELEMENTS
# SUPERVISING
# ELEMENTS
b) DISTURBANCE DETECTOR
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PATH: SETTINGS GROUPED ELEMENTS
# DISTURBANCE
# DETECTOR
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The Disturbance Detector element is an 87L-dedicated sensitive current disturbance detector that is used to detect any dis-
turbance on the protected system. This detector is intended for such functions as trip output supervision and starting oscil-
lography The Disturbance Detector also signals the 87L function that a disturbance (possible fault) occurred and to resize
the operating window to remove the pre-fault current. It is essential to have the Disturbance Detector enabled for applica-
tions where the 87L operating time is critical.
If the disturbance detector is used to supervise the operation of the 87L function, it is recommended that the 87L Trip logic
element be used. The
ting.
The Disturbance Detector function measures the magnitude of the negative sequence current (I_2), the magnitude of the
zero sequence current (I_0), the change in negative sequence current (∆I_2), the change in zero sequence current (∆I_0),
and the change in positive sequence current (∆I_1). The DD element uses the same source of computing currents as that
for the current differential scheme 87L.
The Adaptive Level Detector operates as follows:
• When the absolute level increases above 0.12 pu for I_0 or I_2, the Adaptive Level Detector output is active and the
next highest threshold level is increased 8 cycles later from 0.12 to 0.24 pu in steps of 0.02 pu. If the level exceeds
0.24 pu, the current Adaptive Level Detector setting remains at 0.24 pu and the output remains active (as well as the
DD output) when the measured value remains above the current setting.
• When the absolute level is decreasing from in range from 0.24 to 0.12 pu, the lower level is set every 8 cycles without
the Adaptive Level Detector active. Note that the 50DD output remains inactive during this change as long as the delta
change is less than 0.04 pu.
The Delta Level Detectors (∆I) detectors are designed to pickup for the 0.04 pu change in I_1, I_2, and I_0 currents. The ∆I
is measured by comparing the present value to the value calculated 4 cycles earlier.
• DD FUNCTION: This setting is used to enable/disable the operation of the Disturbance Detector.
• DD NON-CURRENT SUPV: This setting is used to select a FlexLogic™ operand which will activate the output of the
Disturbance Detector upon events (such as frequency or voltage change) not accompanied by a current change.
5-148
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SETTING GROUP 1(6)
# DISTURBANCE
# DETECTOR
# OPEN POLE DETECTOR
MESSAGE
#
# 87L TRIP
MESSAGE
#
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SETTING GROUP 1(6)
DD
FUNCTION: Disabled
DD NON-CURRENT SUPV:
MESSAGE
Off
DD CONTROL LOGIC:
MESSAGE
Off
DD LOGIC SEAL-IN:
MESSAGE
Off
DD
MESSAGE
EVENTS: Disabled
disturbance detector FlexLogic™ operand must then be assigned to an
50DD SV
L90 Line Differential Relay

5.5.14 SUPERVISING ELEMENTS

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SUPERVISING ELEMENTS
See page 5-148.
See page 5-150.
See page 5-152.
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SUPERVISING ELEMENTS
Range: Disabled, Enabled
Range: FlexLogic™ operand
Range: FlexLogic™ operand
Range: FlexLogic™ operand
Range: Disabled, Enabled
5 SETTINGS
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DISTURBANCE DETECTOR
set-
87L TRIP SUPV
GE Multilin