Toshiba GRL100-701B Instruction Manual page 45

Z3S
Z2S
Z1S
BRRS
ZRS
Z4S
(
a) Phase fault element
Figure 2.3.1.3 shows typical time-distance characteristics of the time-stepped distance protection
provided at terminal A.
Zone 1 is set to cover about 80% of the protected line. When GRL100 is used as the main
protection, zone 1 generally provides instantaneous tripping but if used as a backup protection,
time delayed tripping can be provided. With the GRL100, 6 types of zone 1 tripping modes can be
set using the trip mode setting switch [Z1CNT].
Zone 2 is set to cover about 120% or more of the protected line, providing protection for the rest of
the protected line not covered by zone 1 and backup protection of the remote end busbar. In order
to coordinate the fault clearance time by the main protection, with the zone 1 protection of the
adjacent lines or by the remote end busbar protection, zone 2 carries out time delayed tripping.
Zone 2 trip can be disabled by the scheme switch [Z2TP].
Reverse Zone R
∼
Figure 2.3.1.3 Time/Distance Characteristics of Time-Stepped Distance Protection
Zone 3 is mainly provided for remote backup protection of adjacent lines. Its reach is set to at least
1.2 times the sum of the impedance of the protected line and the longest adjacent line. The zone 3
time delay is set so that it coordinates with the fault clearance time provided by zone 2 of adjacent
lines.
The reverse looking zone R element is used for time delayed local backup protection for busbar
faults and transformer faults. Furthermore, when applied to multi-terminal lines, it is effective as
the backup protection for adjacent lines behind the relaying point instead of the zone 3 protection
BFRS
BFR2S
BFR1S
BRLS
Figure 2.3.1.2 Quadrilateral Characteristics
Time
TR
T3
T2
Zone 1
T1
A
 44 
Z3G
BFR2G
Z2G
BFR1G
Z1G
BRRG
ZRG BRLG
Z4G
(b) Earth fault element
Zone 3
Zone 2
B
6 F 2 S 0 8 5 0
BFRG
∼
C