GE 845

4–138 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION CHAPTER 4: SETPOINTS
Protection
The 845 protection elements are organized in six (6) identical setpoint groups: Setpoint
Group 1 to Setpoint Group 6.
Figure 4-45: Protection Display Hierarchy
Each Setpoint Group has the same protection functions, depending on the relay order
code.
Transformer Elements
• Percent Differential
• Transformer Overload
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)
• Restricted Ground (Earth) Fault (87G)
• Negative Sequence Time Overcurrent Protection (51_2)
• Negative Sequence Instantaneous Overcurrent Protection (50_2)
Voltage Elements
Setpoints
Device
System
Inputs
Outputs
Protection
Monitoring
Control
FlexLogic
Data Capture
Level 1 Level 2 Level 3 Level 4
Data Capture
Power
Frequency
Voltage
Current
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Transformer
Percent Differential
Testing