GE D90 Plus Instruction Manual page 229

CHAPTER 7: PROTECTION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Seal-In Delay
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.400 seconds
The out-of-step trip FlexLogic operand
period of time. The sealing-in is crucial in the delayed trip mode, as the original trip signal
is a very short pulse occurring when the impedance locus leaves the outer characteristic
after the out-of-step sequence is completed.
Trip Mode
Range: Early, Delayed
Default: Delayed
Selection of the "Early" trip mode results in an instantaneous trip after the last step in the
out-of-step tripping sequence is completed. The early trip mode stresses the circuit
breakers as the currents at that moment are high (the electromotive forces of the two
equivalent systems are approximately 180° apart). Selection of the "Delayed" trip mode
results in a trip at the moment when the impedance locus leaves the outer
characteristic. Delayed trip mode relaxes the operating conditions for the breakers as
the currents at that moment are low. Make the selection considering the capability of the
breakers in the system.
Block
Range: any FlexLogic operand
Default: Off
This setting selects the FlexLogic operand used for blocking the out-of-step function
only. The power swing blocking function is operational all the time as long as the
element is enabled. The blocking signal resets the output
does not stop the out-of-step tripping sequence.
Events
Range: Enabled, Disabled
Default: Enabled
This setting enables and disables the logging of power swing detect events in the
sequence of events recorder.
Figure 192: Power swing detect scheme logic, sheet 1 of 3
GROUPED PROTECTION ELEMENTS
(POWER SWING TRIP) is sealed-in for the specified
POWER SWING TRIP
operand but
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