Negative Sequence Current - GE G60 Instruction Manual

5 SETTINGS
a) NEGATIVE SEQUENCE DIRECTIONAL OVERCURRENT (ANSI 67_2)
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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 for-
ward 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
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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: 0.125
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
G60 Generator Management Relay

5.5.9 NEGATIVE SEQUENCE CURRENT

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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
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NEG SEQ DIR OC1(2)
Ω
in steps of 0.01
and
NEG SEQ DIR OC1 REV
(EQ 5.23)
5-113
5
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