A communication signal is sent (CS) if a fault is detected by zone 2 (overreach zone).
When a communication signal is received (CR) zone 2 operates instantaneously. The logic
is shown in figure 13.
Send signal (CS)
AND
OR
Trip
ANSI11000076_2_en.vsd
ZQMPDIS (21)
Receive signal (CR)
Zone 1 TRIP
Zone 1 PICKUP
Zone 2 TRIP
Zone 2 PICKUP
ANSI11000076 V2 EN
Figure 13: Logic of over-reach communication scheme
This scheme is used for short lines where it can not be assured that the zone 1 reach from
both line ends overlap each other. The scheme should also be used for lines where the fault
current infeed from one of the line ends is small and the weak end infeed logic is used.
3.1.6.2 Principles for under-reach permissive communication logic
The principle of the logic can be explained as shown in figure
14.
Z 1 = R 1 + jX 1
Z 0 = R 0 + jX0
A B
Zone 1
Zone 2
C
Zone 1
Zone 2
Communication
Y
Y
REL 650
REL 650
ANSI11000111_1_en.vsd
ANSI11000111 V1 EN
Figure 14: Principle of under-reach communication scheme
1MRK 506 334-UUS A Section 3
REL650 setting examples
59
Application manual
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