GE 889 Instruction Manual page 377

CHAPTER 4: SETPOINTS
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
8. Using the results of the transient stability analysis, find the PICKUP DELAY, which is
shorter than the time required for the impedance locus to travel between the left and
right blinders during the fastest expected out-of-step. As is suggested by IEEE
Standard C37.102, a timer setting of 40 ms to 100 ms is appropriate if a stability study
is not available.
9. Validate the settings with the transient stability study cases.
Figure 4-96: A Typical Out-of-step Setting
Path: Setpoints > Protection > Group 1(6) > Impedance > Out of Step
FUNCTION
Range: Disabled, Trip, ALarm, Latched Alarm, Configurable
Default: Disabled
SIGNAL INPUT
Range: Positive Impedance 1, Positive Impedance 2
Default: Positive Impedance 1
This setting provides the selection for the positive sequence impedance which is
calculated by terminal side or neutral side CT. Positive sequence impedance 1 is
calculated using 3-phase J1 currents and 3-phase J2 voltages. Positive sequence
impedance 2 is calculated using 3-phase K1 currents and 3-phase J2 voltages.
MHO FORWARD REACH
Range: 0.10 to 500.00 ohms in steps of 0.01 ohms
Default: 2.00 ohms
This setting specifies the forward reach of the mho characteristic. The reach impedance
is entered in secondary ohms. The reach impedance angle is fixed to 90 degrees.
MHO REVERSE REACH
Range: 0.10 to 500.00 ohms in steps of 0.01 ohms
Default: 2.00 ohms
This setting specifies the reverse reach of the mho characteristic. The reach impedance
is entered in secondary ohms. The reach impedance angle is fixed to -90 degrees.
PROTECTION
4–247