Technical description
2 Protection functions
2.20 Circuit breaker failure stage
CBFP (50BF)
VM50.EN004
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Setting parameters of second harmonic blocking 2.Ha(51F2):
Parameter Value
Unit
Default
Description
If2>
10…100
%
10
Setting value If2/Ifund
t_f2
0.05…300.0 s
0.05
Definite operating time
S_On
Enabled;
Disabled
- Enabled
Start
on
event
S_Off
Enabled;
Disabled
-
Enabled
Start off event
T_On
Enabled;
Disabled
- Enabled
Trip
on
event
T_Off
Enabled;
Disabled
-
Enabled
Trip off event
Measured and recorded values of second harmonic
blocking 2.Ha(51F2):
Parameter Value Unit Description
IL1H2.
%
2. harmonic of IL1,
proportional to the
fundamental value of
IL1
IL2H2.
%
2. harmonic of IL2
Measured
values
IL3H2.
%
2. harmonic of IL3
Recorded
values
Flt
%
The max. fault value
EDly
%
Elapsed time as
compared to the set
operating time; 100%
= tripping
2.20.
Circuit breaker failure stage CBFP
(50BF)
The circuit breaker failure protection can be used to trip any
upstream circuit breaker (CB), if the fault has not disappeared
within a given time after the initial trip command. A different
output contact of the device must be used for this backup trip.
The operation of the circuit-breaker failure protection (CBFP)
is based on the supervision of the signal to the selected trip
relay and the time the fault remains on after the trip command.
If this time is longer than the operating time of the CBFP
stage, the CBFP stage activates another output relay, which
will remain activated until the primary trip relay resets.
The CBFP stage is supervising all the protection stages using
the same selected trip relay, since it supervises the control
signal of this relay. See chapter 5.4 for details about the output
matrix and the trip relays.