CYG PRS-7367 - 50 BF Application Scope; 50 BF Settings

Protection Functions
PRS-7367 73
breaker is opened and the moment when the measured current is detected to be under the set
value
• Additional safety margin (t
Margin
), which is to avoid unintentional operation of circuit breaker failure
protection.
The time delay for the backup trip(50BF_BFTrBu_T) must be longer compared to the retrip time so
that the unwanted backup tripping can be avoided.
3.7.3 50BF Application Scope
50BF can retrip and breaker failure trip. This means that a second trip signal is sent to the
protected circuit breaker. These functions are used to increase the operational reliability of the
breaker. The function can also be used to avoid backup tripping of several breakers in case
mistakes occur during IED maintenance and tests.
The breaker failure function and dead zone function issue a backup trip command to upstream
circuit breakers in case the original circuit breaker fails to trip for the protected component. The
detection of a failure to break the current through the breaker is made by measuring the current or
by detecting the remaining trip signal.
3.7.4 50BF Settings
Table 3.7-4 50BF settings
No.
Name
Values(Range
)
Unit
Step
Default
Description
1
50BF_Ena
0-1
-
1
1
Operation Enable/Disable
2
50BF_ReTr_Ctl
0-2
-
1
1
Retrip Control Logic Setting:
=0: Disable
=1: Without Check
=2: Check
3
50BF_BFTr_Ena
0-1
-
1
1
Enable signal of BF trip CB logic
4
50BF_BFTrBu_Ena
0-1
-
1
1
Enable signal of BF trip backup
CB logic
5
50BF_DZTrBu_Ena
0-1
-
1
1
Enable signal of Dead zone trip
backup CB logic
6
50BF_ResCur_Ena
0-1
-
1
1
Enable signal of zero sequence
current logic
7
50BF_NegCur_Ena
0-1
-
1
1
Enable signal of negative current
logic
8
50BF_QuickRet_Ena
0-1
-
1
1
Enable quick return the
operation
9
50BF_Cur_Str
0.04 – 20.00
A
0.01
20
Operating phase current
10
50BF_ResCur_Str
0.04 – 20.00
A
0.01
20
Operating residual current
11
50BF_NegCur_Str
0.04 – 20.00
A
0.01
20
Operating negative current
12
50BF_DeaCur_Str
0.04 – 20.00
A
0.01
20
Operating Dead zone current
13
50BF_CBFault_T
0.00 - 60.00
s
0.01
5
Time delay of circuit breaker