GE L60, Instruction Manual, Page: 191 / 498

GE Multilin L60 Line Phase Comparison Relay 5-99
5 SETTINGS 5.5 GROUPED ELEMENTS
5
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 com-
posed 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 principles
of distance relaying – may be inaccurate in such conditions. Ground distance Zones through apply additional zero-
sequence directional supervision. See Chapter 8 for additional details.
Three zones of ground distance protection are provided. Each zone is configured individually through its own setting menu.
All of the settings can be independently modified for each of the zones except:
1. The
SIGNAL SOURCE
setting (common for both phase and ground elements for all zones as entered under the
SETTINGS
GROUPED ELEMENTS SETTING GROUP 1(6) DISTANCE
menu).
2. The
MEMORY DURATION
setting (common for both phase and ground elements for all zones as entered under the
SET-
TINGS GROUPED ELEMENTS SETTING GROUP 1(6) DISTANCE
menu).
The common distance settings noted at the start of the Distance section must be properly chosen for correct operation of
the ground distance elements.
Although all three zones can be used as either instantaneous elements (pickup [
PKP
] and dropout [
DPO
] FlexLogic™ sig-
nals) or time-delayed elements (operate [
OP
] FlexLogic™ signals), only Zone 1 is intended for the instantaneous under-
reaching tripping mode.
Ensure that the
PHASE VT SECONDARY VOLTAGE
(see the
SETTINGS SYSTEM SETUP AC INPUTS VOLTAGE
BANK
menu) is set correctly to prevent improper operation of associated memory action.
• GND DIST Z1 DIR: All three zones are reversible. The forward direction is defined by the
GND DIST Z1 RCA
setting 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
and
GND DIST Z1 RCA
settings, and the reverse reach impedance defined
by the
GND DIST Z1 REV REACH
and
GND DIST Z1 REV REACH RCA
settings.
• GND DIST Z1 SHAPE: This setting selects the shape of the ground distance characteristic between the mho and
quadrilateral characteristics. The selection is available on a per-zone basis.
The directional and non-directional quadrilateral ground distance characteristics are shown below. The directional and
non-directional mho ground distance characteristics are the same as those shown for the phase distance element in
the previous sub-section.
MESSAGE
GND DIST Z1 VOLT
LEVEL: 0.000 pu
Range: 0.000 to 5.000 pu in steps of 0.001
MESSAGE
GND DIST Z1
DELAY:0.000 s
Range: 0.000 to 65.535 s in steps of 0.001
MESSAGE
GND DIST Z1 BLK:
Off
Range: FlexLogic™ operand
MESSAGE
GND DIST Z1
TARGET: Self-Reset
Range: Self-Rest, Latched, Disabled
MESSAGE
GND DIST Z1
EVENTS: Disabled
Range: Disabled, Enabled
WARNING