CYG PRS-7367 - Circuit breaker failure protection 50 BF

Protection Functions
PRS-7367 65
No.
Name
Values(Range
)
Unit
Step
Default
Description
4
SOTF_Cur_Dead_Line
0.04In – 20In
A
0.01In
0.2In
Dead line Current setting value
5
SOTF_Vol_Dead_Line
30 – 100
V
1
30
Dead line Voltage setting value
6
SOTF_Dead_Line_T
0.03 - 60.00s
s
0.01
0.2
time delay for dead line
7
SOTF_CurVol_Det_T
0.03 - 60.00
s
0.01
0.03
Time delay for voltage and current
based detection
8
SOTF_Ext_Dly_T
0.03 - 120.00
s
0.01
0.03
SOTF start time delay
9
SOTF_Reset_T
0.00 - 60.00
s
0.01
1
SOTF reset time delay
3.7 Circuit breaker failure protection 50BF
3.7.1 50BF Overview
This relay provides a circuit breaker failure function with a definite time characteristic. The circuit
breaker failure protection is specially applied for re-tripping the circuit breaker, when the relay has
transmitted the tripping command to the circuit breaker, but the fault is still existed in the system or
the circuit breaker is still closed after an appointed time delay.
The breaker failure protection in this relay has four independent definite time delay characteristics,
including two stages of its own breaker through both of the tripping coils: one is for repeating
tripping, and another is breaker failure tripping; and two stages for tripping logic operation of the
electrically-adjacent breakers: one is breaker failure tripping, and another is dead zone tripping.
For some special faults (for example, overvoltage protection operating), maybe the faulty current is
very small and the current criterion of the breaker failure protection cannot be satisfied, in order to
ensure the breaker failure protection can operate in such a situation, the auxiliary contact of the
circuit breaker can be taken into account.
3.7.1.1 Function Block
The function block of the protection is as below.