GE MiCOM P40 Agile User Manual

5 ZONE1 EXTENSION SCHEME
Auto-reclosure is widely used on radial overhead line circuits to re-establish supply following a transient fault. A
Zone 1 extension scheme may be applied to a radial overhead feeder to provide high speed protection for
transient faults along the whole of the protected line. The figure below shows the alternative reach selections for
zone 1: Z1 or the extended reach Z1X.
E02739
Z1 Extension (B)
Z1 Extension (A)
B
A
Z1A
ZL
Figure 144: Zone 1 extension scheme
In this scheme Zone 1X is enabled and set to overreach the protected line. A fault on the line, including one in the
end 20% not covered by Zone 1, results in instantaneous tripping followed by autoreclosure. Zone 1X has resistive
reaches and residual compensation similar to Zone 1. The autorecloser is used to inhibit tripping from Zone 1X so
that on reclosure the device operates with Basic scheme logic only, to co-ordinate with downstream protection for
permanent faults. Therefore transient faults on the line are cleared instantaneously, which reduces the probability
of a transient fault becoming permanent. However, the scheme can operate for some faults on an adjacent line,
although this is followed by autoreclosure with correct protection discrimination. Increased circuit breaker
operations would occur, together with transient loss of supply to a substation.
Fault trip Z1X time delay
First fault trip = tZ1
Fault trip for persistent fault on auto-reclose = tZ2
The Zone 1 extension scheme can be disabled, permanently enabled or just brought into service when the
communication channel fails and the aided scheme is inoperative. If used in conjunction with a channel-aided
scheme, Z1X can be set to be enabled when Ch1 or Ch2 fails, or when all channels fail, or when any channel fails.
V02754
Reset Zone 1 Ext
Z1X Active&
1
Z1 Ext Scheme
Enabled
En. on Ch1 Fail
En. on Ch2 Fail
En. All Ch Fail
En. Any Ch Fail
Aid 1 Chan Fail
Aid 2 Chan Fail
&
&
&
&
1
490
317
318
876
Figure 145: Zone 1 extension logic
Chapter 9 - Non-Aided Schemes P543i/P545i
264 P54x1i-TM-EN-1

GE MiCOM P40 Agile Specifications

General

Brand	GE
Model	MiCOM P40 Agile
Category	Control Unit
Language	English