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5.6 GROUPED ELEMENTS
c) NEGATIVE SEQUENCE DIRECTIONAL OVERCURRENT (ANSI 67Q, IEC PDEF/PTOC)
PATH: SETTINGS
GROUPED ELEMENTS
NEG SEQ DIR OC1
5
There are two negative-sequence directional overcurrent protection elements available. The element provides both forward
and reverse fault direction indications through its output operands
respectively. The output operand is asserted if the magnitude of the operating current is above a pickup level (overcurrent
unit) and the fault direction is seen as forward or reverse, respectively (directional unit).
The overcurrent unit of the element essentially responds to the magnitude of a fundamental frequency phasor of either
the negative-sequence or zero-sequence current as per user selection. The zero-sequence current should not be mistaken
with the neutral current (factor 3 difference).
A positive-sequence restraint is applied for better performance: a small user-programmable portion of the positive-
sequence current magnitude is subtracted from the negative or zero-sequence current magnitude, respectively, when form-
ing the element operating quantity.
The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious negative-sequence and
zero-sequence currents resulting from:
•
System unbalances under heavy load conditions.
•
Transformation errors of current transformers (CTs).
•
Fault inception and switch-off transients.
5-218
SETTING GROUP 1(6)
NEG SEQ DIR OC1
FUNCTION: Disabled
NEG SEQ DIR OC1
MESSAGE
SOURCE: SRC 1
NEG SEQ DIR OC1
MESSAGE
OFFSET: 0.00
NEG SEQ DIR OC1
MESSAGE
TYPE: Neg Sequence
NEG SEQ DIR OC1 POS-
MESSAGE
SEQ RESTRAINT: 0.063
NEG SEQ DIR OC1 FWD
MESSAGE
ECA: 75° Lag
NEG SEQ DIR OC1 FWD
MESSAGE
LIMIT ANGLE: 90°
NEG SEQ DIR OC1 FWD
MESSAGE
PICKUP:
NEG SEQ DIR OC1 REV
MESSAGE
LIMIT ANGLE: 90°
NEG SEQ DIR OC1 REV
MESSAGE
PICKUP:
NEG SEQ DIR OC1 BLK:
MESSAGE
Off
NEG SEQ DIR OC1
MESSAGE
TARGET: Self-reset
NEG SEQ DIR OC1
MESSAGE
EVENTS: Disabled
I
I_2
K
I_1
=
–
op
L90 Line Current Differential System
NEGATIVE SEQUENCE CURRENT
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4
Range: 0.00 to 250.00 ohms in steps of 0.01
Range: Neg Sequence, Zero Sequence
Range: 0.000 to 0.500 in steps of 0.001
Range: 0 to 90° Lag in steps of 1
Range: 40 to 90° in steps of 1
Range: 0.015 to 30.000 pu in steps of 0.001
0.050 pu
Range: 40 to 90° in steps of 1
Range: 0.015 to 30.000 pu in steps of 0.001
0.050 pu
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
NEG SEQ DIR OC1 FWD
or
I
3
I_0
K
I_1
=
–
op
5 SETTINGS
NEG SEQ DIR OC1(2)
and
NEG SEQ DIR OC1 REV
GE Multilin
,
(EQ 5.30)
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