GE Multilin 850

CHAPTER 4: SETPOINTS PROTECTION
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–113
Current Elements
Figure 4-43: Current Elements Display Hierarchy
Description
The relay has six setpoint groups with two phase, two neutral, one ground, one sensitive
ground, and one negative sequence time overcurrent elements per group. The
programming of the time-current characteristics of these elements is identical in all cases
and is only covered in this section. The required curve is established by programming a
Pickup Current, Curve Shape, Curve Multiplier, and Reset Time. The Curve Shape can be
either a standard shape or a user-defined shape programmed with the FlexCurve feature.
Accurate coordination may require changing the time overcurrent characteristics of
particular elements under different conditions. For manual closing or picking up a cold
load, a different time-current characteristic can be produced by increasing the pickup
current value. In the 850
relay, the pickup current can be raised between autoreclose
shots.
The relay has six setpoint groups. The programming of the time-current characteristics of
these elements is identical in all cases and is only covered in this section. The required
curve is established by programming a Pickup Current, Curve Shape, Curve Multiplier, and
Reset Time. The Curve Shape can be either a standard shape or a user-defined shape
programmed with the FlexCurve feature. Accurate coordination may require changing the
time overcurrent characteristics of particular elements under different conditions.
Setpoints
Device
System
Inputs
Outputs
Protection
Monitoring
Control
FlexLogic
Data Capture
Group 1
Phase IOC
Phase TOC
Neutral TOC
Phase Directional OC
Neutral Directional OC
Neutral IOC
Ground IOC
Ground TOC
Negative Sequence TOC
Ground Directional OC
Negative Sequence Dir. OC
Negative Sequence IOC
Load Encroachment
Broken Conductor
Cable Thermal Model
Level 1 Level 2 Level 3 Level 4
Restricted Ground Fault
Sensitive Ground IOC
Sensitive Ground TOC
Sens. Ground Directional OC
Level 5
Data Capture
Power
Frequency
Voltage
Current
Group 2
Group 3
Group 4
Group 5
Group 6
Testing
Feeder
Switch On To Fault