GE D90 Plus Instruction Manual page 289

CHAPTER 7: PROTECTION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Neutral Current High-Set Pickup
Range: 0.001 to 30.000 pu in steps of 0.001
Default: 1.050 pu
This setting specifies the neutral current output supervision level. Generally, this setting
should detect the lowest expected fault current on the protected breaker, before a
breaker opening resistor is inserted. Neutral current supervision is used only in the three
pole scheme to provide increased sensitivity. This setting is valid only for three-pole
breaker failure schemes.
Phase Current Low-Set Pickup
Range: 0.001 to 30.000 pu in steps of 0.001
Default: 1.050 pu
This setting specifies the phase current output supervision level. Generally, this setting
should detect the lowest expected fault current on the protected breaker, after a breaker
opening resistor is inserted (approximately 90% of the resistor current).
Neutral Current Low-Set Pickup
Range: 0.001 to 30.000 pu in steps of 0.001
Default: 1.050 pu
This setting specifies the neutral current output supervision level. Generally, this setting
should detect the lowest expected fault current on the protected breaker, after a breaker
opening resistor is inserted (approximately 90% of the resistor current). This setting is
valid only for three-pole breaker failure schemes.
Low-Set Time Delay
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.000 seconds
This setting specifies the pickup delay for current detection after opening resistor
insertion.
Trip Dropout Delay
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.000 seconds
This setting specifies the time for which the trip output is sealed-in. This timer must be
coordinated with the automatic reclosing scheme of the failed breaker, to which the
breaker failure element sends a cancel reclosure signal. Reclosure of a remote breaker
can also be prevented by holding a transfer trip signal on longer than the reclaim time.
Events
Range: Enabled, Disabled
Default: Enabled
This setting enables and disables the logging of breaker failure events in the sequence of
events recorder.
Phase A Initiate, Phase B Initiate, Phase C Initiate
Range: any FlexLogic™ operand or shared operand
Default: Off
These settings select operands to initiate phase A, B, and C single-pole tripping of the
breaker and the phase A, B, or C portion of the scheme, accordingly. These settings are
only valid for single-pole breaker failure schemes.
GROUPED PROTECTION ELEMENTS
279