GE P444 User Manual

Application Notes
P44x/EN AP/Hb
6
MiCOM P40 Agile P442, P444
(AP) 5-
105
&
&
&
&
1
1
&
Vr>threshold
Ied threshold
Forward decision
Reverse decision
Iev threshold
Single phase selection
2 Pole or 3 Pole Selection
1 pole dead
Z< starting
Independant
channels DIST/DEF
Tripping Mode
0
T
t-cycle
Forward Startup
Single Phase Trip
Three Phase Trip
&
0
T
t-trans
&
Carrier Received DEF
Blocking DEF
&
0
T
t-delay
Reverse decision
Vr>threshold
&
&
Three
Reversal Startup
Blocking Carrier Send
Single
P3043ENa
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.

GE P444 Specifications

General

Brand	GE
Model	P444
Category	Protection Device
Language	English