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18
LPS-O Line Protection System GE Power Management
2.3 PROTECTION SETTINGS 2 CALCULATION OF SETTINGS
2
614: 51GCURVE - Select 51G Characteristic Curve
51GCURVE
determines the characteristic curve shape for the
51G
function. The choices are inverse curve
(INV
;
see Figure 2–14: INVERSE CURVE on page 2–29), very inverse curve (V-INV; see Figure 2–15: VERY
INVERSE CURVE on page 2–30), extremely inverse (E-INV; see Figure 2–16: EXTREMELY INVERSE
CURVE on page 2–31), user-defined custom curve (CUSTOM), and definite time (DEFT).
615: 51GTIMDIAL - Ground Time Overcurrent Time Dial
51GTIMDIAL
selects the time-dial setting for the
51G
function.
51GTIMDIAL
can be set over the range of 0.5
to 10.0. The pickup and time-dial settings should be selected to provide coordination with similar functions in
adjacent line sections.
616: DEFTIMDELY - Definite Time Delay
When the 51G function is selected to have a definite time characteristic,
DEFTIMDELY
determines the associ-
ated fixed time delay. Select a time that meets the specific application.
617: 51G_RESET - Select Time Overcurrent Reset Characteristic
The
51G
function can be set to have a very fast reset (approximately 50 milliseconds for the definite time curve
and 4 milliseconds for the variable time curves) following its pickup, or it can be set to have a reset characteris-
tic that emulates the reset time of an electromechanical device with a similar time curve. Select FAST for the
fast reset or EM to emulate an electromechanical function.
2.3.8 VOLTAGE
701: RATEDVOLTS - Rated Per Unit Voltage
This setting establishes the voltage on which per unit voltage values are based.
RATEDVOLTS
can be set to
100, 105, 110, 115 or 120 volts. Use a setting that is closest to the voltage that is applied to the LPS-O system.
702: PHASEOVER - Select Phase Overvoltage
If the phase overvoltage function is to be used, set
PHASEOVER
= YES, otherwise set
PHASEOVER
= NO.
703: PHOVPICKUP - Phase Overvoltage Pickup
PHOVPICKUP
can be set from 0.0 to 1.4 per unit based on the
RATEDVOLTS
setting. Use a setting that
meets the specific application.
704: PHOVTMDLY - Phase Overvoltage Time Delay
PHOVTMDLY
establishes a time delay that is started when the phase overvoltage function operates.
PHOVT-
MDLY
can be set from 0.0 to 10.0 seconds. Use a setting that meets the specific application.
705: FUSEFAIL - Potential Fuse Failure Blocking
Since a distance or directional function may operate for a full or partial loss of AC potential caused by one or
more blown fuses,
FUSEFAIL
is provided to block distance and directional function tripping when a fuse failure
is detected. If the backup overcurrent functions
50
,
50G
, and
51G
are non-directional they will be allowed to
trip. If
50
,
50G
or
51G
are directional, then they will not be allowed to trip. Figure 2–7: FUSEFAIL FUNCTION
LOGIC DIAGRAM shows the functional logic for the
FUSEFAIL
function.
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