Transient Earth Fault Detection Logic; Transient Earth Fault Detection Logic Overview; Figure 141: Transient Earth Fault Logic Overview - GE MiCOM P40 Agile Technical Manual

Chapter 12 - Power Protection Functions
The VH1 and IH2 components are passed through a sign filter and multiplied to create a reactive power
component in the range of -1 to +1. This is the transient reactive power Q
healthy. If Q < 0, then the forward line is faulty.
tran
There are two modes of operation for the direction detector; Standard and Advanced. Standard mode is used in
most cases and is described here. Advanced mode is for special situations, and involves dynamically altering the
Q thresholds. For details of Advanced mode, please contact General Electric.
tran
The inputs to this module are:
● The residual voltage
The residual current
●
Dir> Vnf Thresh (defines the threshold for the residual voltage sign filter).
●
Dir> Inf Thresh (defines the threshold for the residual current sign filter
●
The DD outputs two signals to indicate a forward fault and a reverse fault
Sign Filter Thresholds
The Dir> Vnf Thresh setting is used to get the sign of instantaneous voltage value by sign filter. If the input value is
larger than Vnf, the output is +1. If the input value is less than -1*Vnf, the output is -1. Otherwise the output is 0.
The Dir> Inf Thresh setting is used to get the sign of instantaneous current value by sign filter. If the input value is
larger than Vnf, the output is +1. If the input value is less than -1*Vnf, the output is -1. Otherwise the output is 0.
5.2

TRANSIENT EARTH FAULT DETECTION LOGIC

5.2.1

TRANSIENT EARTH FAULT DETECTION LOGIC OVERVIEW

VN
TEF VN> Start
TEF Detection
Enabled
TEF> Timer Block
VN
FTD> VN
FTD> Time Window
FTD> Fault Count
FTD> Status
Enabled
VN
IN
Dir>Vnf Thresh
Dir>Inf Thresh
TEF>Dir Status
Enabled

Figure 141: Transient Earth Fault Logic Overview

272
&
Steady
FA
Fault Type
Detector Module
Intermittent
Forward
TRP
Direction
Detector Module
Reverse
. If Q > 0, then there forward line is
tran tran
&
&
&
&
P14x
TEF> Start
TEF> Steady
TEF> Intermit
TEF>DIR FWD
TEF>DIR REV
V00905
P14xEd1-TM-EN-1