GE G60 Instruction Manual page 225

5 SETTINGS
• NEG SEQ DIR OC1 OFFSET: This setting specifies the offset impedance used by this protection. The primary applica-
tion for the offset impedance is to guarantee correct identification of fault direction on series compensated lines (see
the Application of Settings chapter for information on how to calculate this setting). In regular applications, the offset
impedance ensures proper operation even if the negative-sequence voltage at the relaying point is very small. If this is
the intent, the offset impedance shall not be larger than the negative-sequence impedance of the protected circuit.
Practically, it shall be several times smaller. The offset impedance shall be entered in secondary ohms. See the Theory
of Operation chapter for additional details.
• NEG SEQ DIR OC1 TYPE: This setting selects the operating mode for the overcurrent unit of the element. The
choices are "Neg Sequence" and "Zero Sequence". In some applications it is advantageous to use a directional nega-
tive-sequence overcurrent function instead of a directional zero-sequence overcurrent function as inter-circuit mutual
effects are minimized.
• NEG SEQ DIR OC1 POS-SEQ RESTRAINT: This setting controls the amount of the positive-sequence restraint. Set
to 0.063 (in "Zero Sequence" mode) or 0.125 (in "Neg Sequence" mode) for backward compatibility with firmware revi-
sion 3.40 and older. Set to zero to remove the restraint. Set higher if large system unbalances or poor CT performance
are expected.
• NEG SEQ DIR OC1 FWD ECA: This setting select the element characteristic angle (ECA) for the forward direction.
The element characteristic angle in the reverse direction is the angle set for the forward direction shifted by 180°.
• NEG SEQ DIR OC1 FWD LIMIT ANGLE: This setting defines a symmetrical (in both directions from the ECA) limit
angle for the forward direction.
• NEG SEQ DIR OC1 FWD PICKUP: This setting defines the pickup level for the overcurrent unit in the forward direc-
tion. Upon
NEG SEQ DIR OC1 TYPE
selecting this setting it must be kept in mind that the design uses a 'positive-sequence restraint' technique.
• NEG SEQ DIR OC1 REV LIMIT ANGLE: This setting defines a symmetrical (in both directions from the ECA) limit
angle for the reverse direction.
• NEG SEQ DIR OC1 REV PICKUP: This setting defines the pickup level for the overcurrent unit in the reverse direc-
tion. Upon
NEG SEQ DIR OC1 TYPE
selecting this setting it must be kept in mind that the design uses a 'positive-sequence restraint' technique.
SETTING
NEG SEQ DIR OC1
FUNCTION:
Disabled=0
Enabled=1
SETTING
AND
NEG SEQ DIR OC1 BLK:
Off=0
SETTING
NEG SEQ DIR OC1
SOURCE:
Neg Seq Voltage (V_2)
Neg Seq Seq Crt (I_2)
Zero Seq Seq Crt (I_0)
SETTING
NEG SEQ DIR OC1
TYPE:
Neg Sequence
Zero Sequence
Figure 5–70: NEGATIVE SEQUENCE DIRECTIONAL OC1 SCHEME LOGIC
GE Multilin
selection, this pickup threshold applies to zero- or negative-sequence current. When
selection, this pickup threshold applies to zero- or negative-sequence current. When
SETTING
NEG SEQ DIR OC1 FWD
PICKUP:
NEG SEQ DIR OC1 POS-
SEQ RESTRAINT:
AND RUN
_0 - K _1 PICKUP
I I
OR
AND RUN
_2 - K _1 PICKUP
AND
I I
SETTINGS
NEG SEQ DIR OC1 FWD
ECA:
NEG SEQ DIR OC1 FWD
LIMIT ANGLE:
NEG SEQ DIR OC1 REV
LIMIT ANGLE:
NEG SEQ DIR OC1
OFFSET:
RUN FWD
FWD
REV.
V_2 pol
REV
Voltage Polarization
SETTING
NEG SEQ DIR OC1 REV
AND
PICKUP:
NEG SEQ DIR OC1 POS-
SEQ RESTRAINT:
OR
AND
RUN
_2 - K _1 PICKUP
I I
AND RUN
_0 - K _1 PICKUP
I I
G60 Generator Management Relay
5.5 GROUPED ELEMENTS
FLEXLOGIC OPERAND
AND NEG SEQ DIR OC1 FWD
1.25 cy
AND
1.5 cy
FLEXLOGIC OPERAND
NEG SEQ DIR OC1 REV
5
827091A4.CDR
5-127