Under-Reach Permissive Logic - ABB REL650 Applications Manual

Section 3
REL650 setting examples
3.1.11.2
76
A communication signal is sent (CS) if a fault is detected by step 2 (3I
When a communication signal is received (CR) Step 2 (3I
The logic is shown in figure 26.
EF4PTOC (51N_67N)
Step 1 PUST1
Step 2
Receive signal (CR)
ANSI11000078 V1 EN
Figure 26: Logic for four step residual overcurrent protection overreach
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.

Under-reach permissive logic

The principle of the logic can be explained as shown in figure 27.
Step 1 TRIP
Step 2 TRIP
PUST2
1MRK 506 334-UUS A
>> overreach step).
0
>>) operates instantaneously.
0
Send signal (CS)
OR
AND
ANSI11000078_1_en.vsd
Application manual
Trip