GE L60 Instruction Manual page 261

5 SETTINGS
d) NEGATIVE SEQUENCE DIRECTIONAL OVERCURRENT (ANSI 67_2)
PATH: SETTINGS GROUPED ELEMENTS
NEG SEQ DIR OC1
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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
forming the element operating quantity.
The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious negative- and zero-
sequence currents resulting from:
• System unbalances under heavy load conditions.
• Transformation errors of current transformers (CTs).
• Fault inception and switch-off transients.
GE Multilin
SETTING GROUP 1(6)
NEG SEQ DIR OC1
FUNCTION: Disabled
NEG SEQ DIR OC1
SOURCE: SRC 1
NEG SEQ DIR OC1
OFFSET: 0.00 Ω
NEG SEQ DIR OC1
TYPE: Neg Sequence
NEG SEQ DIR OC1 POS-
SEQ RESTRAINT: 0.063
NEG SEQ DIR OC1 FWD
ECA: 75° Lag
NEG SEQ DIR OC1 FWD
LIMIT ANGLE: 90°
NEG SEQ DIR OC1 FWD
PICKUP: 0.05 pu
NEG SEQ DIR OC1 REV
LIMIT ANGLE: 90°
NEG SEQ DIR OC1 REV
PICKUP: 0.05 pu
NEG SEQ DIR OC1 BLK:
Off
NEG SEQ DIR OC1
TARGET: Self-reset
NEG SEQ DIR OC1
EVENTS: Disabled
×
I I_2 K I_1 or I
= –
op
L60 Line Phase Comparison Relay
NEGATIVE SEQUENCE CURRENT
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4
Range: 0.00 to 250.00
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: 0.05 to 30.00 pu in steps of 0.01
Range: 40 to 90° in steps of 1
Range: 0.05 to 30.00 pu in steps of 0.01
Range: FlexLogic™ operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
NEG SEQ DIR OC1 FWD
×
I_0 K I_1
= –
op
5.5 GROUPED ELEMENTS
NEG SEQ DIR OC1(2)
Ω
in steps of 0.01
and
NEG SEQ DIR OC1 REV
(EQ 5.24)
5-159
5
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