Sbef – Stand-By Earth Fault (Not Communication-Aided); Aided Directional Earth Fault (Def) Protection Schemes; Directional Comparison Protection Blocking Scheme - GE MiCOM P40 Agile Technical Manual

Application Notes
MiCOM P40 Agile P442, P444
Vr>threshold
Ied threshold
Forward decision
Reverse decision
Carrier Received DE F
Blocking DEF
Single phase selection
Iev threshold
Reverse decision
Vr>threshold
Tripping Mode
1 pole dead
Z< starting
Independant
channels DIST/DEF
2 Pole or 3 Pole Selection
Figure 74: Directional comparison protection blocking scheme
If the DEF directional comparison transmission is selected on the same channel that is used
to transmit distance aided-trip messages, the DEF will have the same tripping logic as the
main protection (permissive or blocking).
4.8.2.1 SBEF – Stand-By earth fault (not communication-aided)
This protection trips the local breaker directly, without an aided-trip signal, if a high
resistance fault remains after a time delay. The time delay varies inversely with the value of
the fault current. The selectable inverse time curves comply with the ANSI and IEC
standards (see Appendix A).
This protection three-pole trips and can block autoreclosing.
Figure 75: SBEF – stand-by earth fault
4.8.3

Aided Directional Earth Fault (DEF) protection schemes

The option of using separate channels for Directional Earth Fault (DEF) aided tripping, and
distance protection schemes, is offered in the P442 and P444 relays.
When a separate channel for DEF is used, the DEF scheme is independently selectable.
When a common signalling channel is employed, the distance and DEF must share a
common scheme. In this case a permissive overreach or blocking distance scheme must be
used. The aided tripping schemes can perform single pole tripping.
&
& &
0
T
t-delay
&
0
1
T
t-cycle
&
Three
0
T
t-trans
&
Single
&
&
1
P44x/EN AP/Hb6
(AP) 5-105
Forward Startup
&
Single Phase T rip
Blocking Carrier Send
Reversal Startup
&
Three Phase T rip
P3043ENa