GE D90 Plus Instruction Manual page 218

GROUPED PROTECTION ELEMENTS
NOTE:
208
Set this setting at least three times the
Settings > Protection > Power System > AC Inputs - Current menu. Zone 1 is sealed in
with the current supervision.
Voltage Level
Range: 0.000 to 5.000 pu in steps of 0.001
Default: 0.000 pu
This setting is relevant for applications on series-compensated lines, or in general, if
series capacitors are located between the relaying point and a point for which the zone
shall not overreach. For plain (non-compensated) lines, set it to zero. Otherwise, the
setting is entered in per unit of the VT bank configured under the distance
setting. Effectively, this setting facilitates dynamic current-based reach reduction. In
non-directional applications, this setting applies only to the forward reach of the non-
directional zone.
The use of dynamic reach control by selection of a non-zero value for the
setting disables the subcycle operating time for that particular zone.
Delay
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.000 seconds
This setting enables the user to delay operation of the distance elements and implement
a stepped distance backup protection. The distance element timer applies a short drop-
out delay to cope with faults located close to the boundary of the zone when small
oscillations in the voltages or currents can inadvertently reset the timer.
Block
Range: any FlexLogic operand
Default: Off
This setting enables the user to select a FlexLogic operand to block the given ground
distance element. VT fuse fail detection is one of the applications for this setting.
Events
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the logging of ground distance events in the sequence
of events recorder.
The following figure shows the ground distance operation scheme for zone 1.
Figure 183: Ground distance zone 1 operation logic
The following figure shows the ground distance operation scheme for zone 2. The logic is
analogous for zones 3 through 5.
Current Cutoff Level
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
setting specified in the
Source
Voltage Level