Current Elements - GE Multilin 850 Instruction Manual

CHAPTER 4: SETPOINTS

Current Elements

850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 4-43: Current Elements Display Hierarchy
Device
System
Inputs
Outputs
Protection
Monitoring
Control
FlexLogic
Testing
Level 1 Level 2
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.
Feeder
Current
Data Capture Voltage
Group 1
Power
Group 2
Data Capture
Frequency
Group 3
Group 4
Group 5
Group 6
Level 3 Level 4
PROTECTION
Phase TOC
Phase IOC
Phase Directional OC
Neutral TOC
Neutral IOC
Neutral Directional OC
Ground TOC
Ground IOC
Ground Directional OC
Sensitive Ground TOC
Sensitive Ground IOC
Sens. Ground Directional OC
Restricted Ground Fault
Switch On To Fault
Negative Sequence TOC
Negative Sequence IOC
Negative Sequence Dir. OC
Broken Conductor
Load Encroachment
Cable Thermal Model
Level 5
4–113