GE L90 Instruction Manual page 360

5.6 GROUPED ELEMENTS
• DD LOGIC SEAL-IN: This setting is used to maintain disturbance detector output for such conditions as balanced
three-phase fault, low level time overcurrent fault, etc. whenever the disturbance detector might reset. Output of the
disturbance detector will be maintained until the chosen FlexLogic operand resets.
The user may disable the
bance on the system which may result in filling the events buffer and possible loss of valuable data.
NOTE
SETTING
DD FUNCTION:
Enabled=1
Disabled=0
ACTUAL
COMPUTE SEQ.
CURRENTS
I_1
I_2
I_0
SETTING
DD CONTROL
LOGIC:
5
Off=0
SETTING
DD LOGIC
SEAL-IN:
Off=0
SETTING
DD NON-CURRENT
SUPV:
Off=0
5-230
setting as the disturbance detector element will respond to any current distur-
DD EVENTS
LOGIC
DELTA LEVEL
DETECTOR
RUN
ABS (I_1-I_1')>0.04 pu
(I_1' is 4 cycles old)
ABS (I_2-I_2')>0.04 pu
(I_2' is 4 cycles old)
ABS (I_0-I_0')>0.04 pu
(I_0' is 4 cycles old)
LOGIC
ADAPTIVE LEVEL
DETECTOR
RUN
AND
I_0 > 0.12 to 0.24 pu
I_2 > 0.12 to 0.24 pu
NOTE:
ADJUSTMENTS ARE
MADE ONCE EVERY
8 CYCLES TO THE
NEXT LEVEL (HIGHER
OR LOWER) IN 0.02 pu
STEPS USING THE
HIGHEST VALUE OF
I_0 AND I_2.
AND
AND
Figure 5–124: DISTURBANCE DETECTOR SCHEME LOGIC
L90 Line Current Differential System
OR
OR
OR
FLEXLOGIC OPERAND
50DD SV
OR
5 SETTINGS
827044A6.CDR
GE Multilin