GE L90 Instruction Manual page 442

GROUPED ELEMENTS
The wattmetric zero-sequence directional element responds to power derived from zero-sequence voltage and current in
5
a direction specified by the element characteristic angle. The angle can be set within all four quadrants, and the power can
be active or reactive. Therefore, the element can be used to sense either forward or reverse ground faults in either
inductive, capacitive, or resistive networks. The inverse time characteristic allows time coordination of elements across the
network.
Typical applications include ground fault protection in solidly grounded transmission networks, grounded/ungrounded/
resistor-grounded/resonant-grounded distribution networks, or for directionalizing other non-directional ground elements.
WATTMETRIC GND FLT 1 VOLT
setting allows selecting between the internally calculated neutral voltage or the externally supplied voltage (broken delta
VT connected to the auxiliary channel bank of the relay). When the latter selection is made, the auxiliary channel must be
identified by the user as a neutral voltage under the VT bank settings. This element operates when the auxiliary voltage is
configured as neutral.
WATTMETRIC GND FLT 1 OV PKP
power measurement. Set this threshold higher than possible unbalance during normal operation of the system. Typically,
this setting is at 0.1 to 0.2 pu for the ungrounded or resonant grounded systems and at 0.05 to 0.1 pu for solidly or resistor-
grounded systems. When using externally supplied voltage via the auxiliary voltage channel, 1 pu is the nominal voltage of
this channel as per VT bank settings. When using internally calculated neutral voltage, 1 pu is the nominal phase to ground
voltage as per the VT bank settings.
WATTMETRIC GND FLT 1 CURR
either calculated internally from the phase currents or supplied externally via the ground CT input from more accurate
sources such as the core balanced CT. This setting allows selecting the source of the operating current.
WATTMETRIC GND FLT 1 OC PKP
sequence power.
WATTMETRIC GND FLT 1 OC PKP DEL
applies to the
WATTMETRIC 1 PKP
WATTMETRIC GND FLT 1 PWR PKP
the 1 pu voltage as specified for the overvoltage condition of this element, and 1 pu current as specified for the
overcurrent condition of this element.
5-256
WATTMETRIC GND FLT 1

OC PKP DEL: 0.20 s
WATTMETRIC GND FLT 1

PWR PKP: 0.100 pu
WATTMETRIC GND FLT 1

REF PWR: 0.500 pu
WATTMETRIC GND FLT 1

ECA: 0° Lag
WATTMETRIC GND FLT 1

PWR PKP DEL: 0.20 s
WATTMETRIC GND FLT 1

CURVE: Definite Time
WATTMETRIC GND FLT 1

MULTIPLIER: 1.00 s
WATT GND FLT 1 BLK:

Off
WATTMETRIC GND FLT 1

TARGET: Self-reset
WATTMETRIC GND FLT 1

EVENTS: Disabled
— The element uses neutral voltage (that is, three times the zero-sequence voltage). This
— This setting specifies the minimum zero sequence voltage supervising the directional
— The element responds to the neutral current (that is, three times zero-sequence current),
— This setting specifies the current supervision level for the measurement of the zero-
— This setting specifies delay for the overcurrent portion of this element. The delay
operand driven from the overcurrent condition.
— This setting specifies the operating point of the element. A value of 1 pu is a product of
Range: 0.00 to 600.00 s in steps of 0.01
Range: 0.001 to 1.200 pu in steps of 0.001
Range: 0.001 to 1.200 pu in steps of 0.001
Range: 0 to 360° Lag in steps of 1
Range: 0.00 to 600.00 s in steps of 0.01
Range: Definite Time, Inverse, FlexCurves A through
D
Range: 0.01 to 2.00 s in steps of 0.01
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS