Negative Sequence Current - GE G60 Instruction Manual

5 SETTINGS
a) NEGATIVE SEQUENCE DIRECTIONAL OVERCURRENT (ANSI 67Q, IEC PDEF/PTOC)
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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 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 neutral current as per user selection.
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.
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: 0.050 pu
NEG SEQ DIR OC1 REV
LIMIT ANGLE: 90°
NEG SEQ DIR OC1 REV
PICKUP: 0.050 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 Protection System

5.6.9 NEGATIVE SEQUENCE CURRENT


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
Range: 40 to 90° in steps of 1
Range: 0.015 to 30.000 pu in steps of 0.001
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
NEG SEQ DIR OC1 FWD
3 × ( I_0 K × I_1 )
= –
op
5.6 GROUPED ELEMENTS

NEG SEQ DIR OC1(2)
and
NEG SEQ DIR OC1 REV
(EQ 5.23)
5-203
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