GE F650 - Page 205

5-58 F650 Digital Bay Controller GEK-106310AB
5.4 PROTECTION ELEMENTS 5 SETTINGS
5
5.4.4.3 NEUTRAL DIRECTIONAL ELEMENT (67N)
The Neutral directional element is used for supervising the neutral (3I0) overcurrent elements. This element can be set to
use either the neutral voltage, or the polarization current measured by the 5
th
current input (Ip), or both as polarization
magnitude.
Table 5–48: 67N ELEMENT SETTINGS
Settings for this element are:
Maximum Torque Angle (MTA): Angle used to rotate the polarization voltage. Positive angles are counter clockwise
rotations, and negative angles are clockwise rotations. The polarization magnitude,
once rotated, defines the MTA line. Vn rotated by this angle points to the semi plane
that corresponds to a Reverse fault. -Vn rotated this angle points to the semi plane
that corresponds to a Forward fault. A typical setting can be –45º.
Directional element direction (Direction): This setting indicates the Direction for which the element will allow a trip.
Depending on this setting, the element will be activated for faults in the forward
direction, or ion the reverse direction, allowing its use in tripping or blocking
schemes. Possible options for this setting are FORWARD and REVERSE.
Polarization type (Polarization): This setting indicates the type of Polarization to be used. The relay can use voltage
polarization (V0), and/or current polarization (Ip). Possible setting values are:
V0 Voltage polarization
Ip Current polarization
V0 + Ip Voltage or current polarization. This allows the element to
operate when any of the polarization magnitudes allow operation.
V0 * Ip Voltage and current polarization. This allows the element to
operate when both polarization magnitudes allow operation.
If the selected polarization type is V0+Ip, then the relay will operate when any of the
polarization magnitudes indicate the selected direction in the Direction setting.
If the selected polarization type is V0*Ip, then the relay will only operate when both
polarization magnitudes indicate the selected direction in the Direction setting.
Polarization Voltage Threshold This is the minimum voltage considered for the direction calculation. Under this
setting, the element will be blocked.
Snapshot Events: The snapshot event setting enables or disables the snapshot event generation for
this elements.
SETPOINT > PROTECTION ELEMENTS > NEUTRAL CURRENT > NEUTRAL DIRECTIONAL >
NEUTRAL DIRECTIONAL 1> NEUTRAL DIRECTIONAL 2 > NEUTRAL DIRECTIONAL 3
SETTING DESCRIPTION NAME DEFAULT VALUE STEP RANGE
Function permission Function DISABLED N/A [DISABLED – ENABLED]
Maximum Torque Angle MTA -45 1 Deg [-90 : +90]
Operation Direction Direction FORWARD N/A [FORWARD – REVERSE]
Polarization type Polarization VO N/A [V
0
– I
P
– V
0
+I
P
– V
0
*I
P
]
Block logic type Block Logic PERMISSION N/A [BLOCK – PERMISSION]
Polarization voltage threshold Pol V Threshold 10 1 V [0 : 300]
Snapshot event generation Snapshot Events ENABLED N/A [DISABLED – ENABLED]