4–112 889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION CHAPTER 4: SETPOINTS
Protection
The 889 protection elements are organized in six (6) identical setpoint groups: Setpoint
Group 1 to Setpoint Group 6.
Figure 4-35: Protection Display Hierarchy
Each Setpoint Group has the same protection functions, depending on the relay order
code.
Generator Elements
• Percent Differential
• Overall Percent Differential
• Generator Unbalance (46)
• Inadvertent Energization (50/27)
• Loss of Excitation (40)
• Loss of Excitation (40)
• Third Harmonic Voltage Difference
• Offline Overcurrent (50OFL)
• Overload Alarm
Current Elements
• Phase Time Overcurrent Protection (51P)
• Phase Instantaneous Overcurrent Protection (50P)
• Phase Directional Overcurrent Protection (67P)
• Neutral Time Overcurrent Protection (51N)
• Neutral Instantaneous Overcurrent Protection (50N)
• Neutral Directional Overcurrent Protection (67N)
• Ground Time Overcurrent Protection (51G)
• Ground Instantaneous Overcurrent Protection (50G)
• Ground Directional Overcurrent Protection (67G)
• Sensitive Ground Time Overcurrent Protection (51SG)
Setpoints
Device
System
Inputs
Outputs
Protection
Monitoring
Control
FlexLogic
Data Capture
Level 1 Level 2 Level 3 Level 4
Data Capture
Power
Frequency
Impedance
Voltage
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Generator
Current
Testing
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