Calculating Settings For Current Reversal And Weak-End Infeed Logic For Residual Overcurrent Protection Ecrwpsch (85) - ABB REL650 Applications Manual

1MRK 506 334-UUS A
3.1.12
Application manual
EF4PTOC (51N_67N)
Step 1 TRIP
Step 1 PUST1
Step 2 TRIP
Step 2 PUST2
Receive signal (CR)
Reverse :
Step 4 TRIP
Step 4 PUREV
ANSI11000080 V1 EN
Figure 30: Logic for four step residual overcurrent protection blocking
communication scheme
The trip signal from step 2 must be delayed so that the blocking signal has enough time for
blocking at external faults.
Calculating settings for current reversal and weak-end infeed
logic for residual overcurrent protection ECRWPSCH (85)
The four step residual overcurrent protection can only operate if the fault current to the fed
to the protection is larger than about 3% of the rated current (settable). There is a risk that
the fault current infeed from one of the line ends is very small, but not zero. In such case
the following can be the consequence of a short circuit close to the line end with small fault
current infeed.
REL650 setting examples
OR
AND
Section 3
Trip
Send signal (CS)
ANSI11000080_1_en.vsd
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