Figure 228: Transient Earth Fault Logic Overview - GE MiCOM P40 Agile Technical Manual

P543i/P545i
The residual voltage (Vres) is passed through a bandpass filter tuned to 220 Hz, which also adds 90° to it. The
residual current (Ires) is also passed through a 220 Hz bandpass filter, but no phase shift is applied. The resulting
components which we shall call V
phase if the forward line is not faulted.
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.
9.2 TRANSIENT EARTH FAULT DETECTION LOGIC
9.2.1 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 228: Transient Earth Fault Logic Overview

P54x1i-TM-EN-1
and I are therefore in antiphase with each other for forward faults and in
H1 H2
&
Steady
FA
Fault Type
Detector Module
Intermittent
Forward
TRP
Direction
Detector Module
Reverse
Chapter 13 - Current Protection Functions
. If Q > 0, then there forward line is
tran tran
&
&
&
&
TEF> Start
TEF> Steady
TEF> Intermit
TEF>DIR FWD
TEF>DIR REV
V00905
393