GE L60 Instructions Manual page 433

CHAPTER 5: SETTINGS
The ground mho distance function uses a dynamic 100% memory-polarized mho characteristic with additional reactance,
directional, current, and phase selection supervising characteristics. The ground quadrilateral distance function is
composed of a reactance characteristic, right and left blinders, and 100% memory-polarized directional, overcurrent, and
phase selection supervising characteristics.
When set to non-directional, the mho function becomes an offset mho with the reverse reach controlled independently
from the forward reach, and all the directional characteristics removed. When set to non-directional, the quadrilateral
function applies a reactance line in the reverse direction instead of the directional comparators.
The reactance supervision for the mho function uses the zero-sequence current for polarization. The reactance line of the
quadrilateral function uses either zero-sequence or negative-sequence current as a polarizing quantity. The selection is
controlled by a user setting and depends on the degree of non-homogeneity of the zero-sequence and negative-sequence
equivalent networks.
The directional supervision uses memory voltage as polarizing quantity and both zero- and negative-sequence currents as
operating quantities.
The phase selection supervision restrains the ground elements during double-line-to-ground faults as they, by the
principles of distance relaying, can be inaccurate in such conditions. Ground distance zones 1 and higher apply additional
zero-sequence directional supervision.
Each ground distance zone is configured individually through its own setting menu. All of the settings can be modified
independently for each of the zones except:
• The setting (common for both phase and ground elements for all zones as entered under the
SIGNAL SOURCE
 GROUPED ELEMENTS  SETTING GROUP 1(6)  DISTANCE
• The setting (common for both phase and ground elements for all zones as entered under the
MEMORY DURATION
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  DISTANCE
The common distance settings noted at the start of this section must be properly chosen for correct operation of the
ground distance elements.
Although all ground distance zones can be used as either instantaneous elements (pickup [
FlexLogic signals) or time-delayed elements (operate [
under-reaching tripping mode.
Ensure that the
PHASE VT SECONDARY VOLTAGE
menu) is set correctly to prevent improper operation of associated memory action.
— All ground distance zones are reversible. The forward direction is defined by the
GND DIST Z1 DIR
and the reverse direction is shifted by 180° from that angle. The non-directional zone spans between the forward reach
impedance defined by the
GND DIST Z1 REACH
the and
GND DIST Z1 REV REACH
— This setting selects the shape of the ground distance characteristic between the mho and
GND DIST Z1 SHAPE
quadrilateral characteristics. The selection is available on a per-zone basis.
The figures show the directional and non-directional quadrilateral ground distance characteristics. The directional and
non-directional mho ground distance characteristics are the same as those shown for the phase distance element in the
previous section.
L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
GND DIST Z1 BLK:

Off
GND DIST Z1

TARGET: Self-reset
GND DIST Z1

EVENTS: Disabled
] FlexLogic signals), only zone 1 is intended for the instantaneous
OP
(see the
and
GND DIST Z1 RCA
settings.
GND DIST Z1 REV REACH RCA
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
menu)
menu)
PKP
SETTINGS  SYSTEM SETUP  AC INPUTS  VOLTAGE BANK
settings, and the reverse reach impedance defined by
GROUPED ELEMENTS
SETTINGS
] and dropout [ ]
DPO
setting
GND DIST Z1 RCA
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