Zone1 Extension Scheme; Figure 113: Zone 1 Extension Scheme; Figure 114: Zone 1 Extension Logic - GE MiCOM P40 Technical Manual

Hide thumbs Also See for MiCOM P40:

Table of Contents

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.

Z1 Extension (B)

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.

First fault trip

Fault trip for persistent fault on auto-reclose

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.

Reset Zone 1 Ext

Z1 Ext Scheme

En. on Ch 1 Fail

En. on Ch 2 Fail

En. All Ch Fail

En. Any Ch Fail

Aid 1 Chan Fail

Aid 2 Chan Fail

P446SV-TM-EN-1

Z1 Extension (A)

Chapter 9 - Non-Aided Schemes

Z1X time delay