• The minimum length of the re-trip pulse, the back-up trip pulse and the back-up
trip pulse 2 are settable. The re-trip pulse, the back-up trip pulse and the back-up
trip pulse 2 will however sustain as long as there is an indication of closed breaker.
• In the current detection it is possible to use three different options: 1 out of 3
where it is sufficient to detect failure to open (high current) in one pole, 1 out of 4
where it is sufficient to detect failure to open (high current) in one pole or high
residual current and 2 out of 4 where at least two current (phase current and/or
residual current) shall be high for breaker failure detection.
• The current detection level for the residual current can be set different from the
setting of phase current detection.
• It is possible to have different back-up time delays for single-phase faults and for
multi-phase faults.
• The back-up trip can be made without current check. It is possible to have this
option activated for small load currents only.
• It is possible to have instantaneous back-up trip function if a signal is high if the
circuit breaker is insufficient to clear faults, for example at low gas pressure.
S
R
SR
Q
OR
AND
AND
30 ms
BFI_3P
BFI_A
OR
OR
BackupTrip A
BFP Started A
Time out A
Reset A
BLOCK
Retrip Time Out A
ANSI09000976-2-en.vsd
0
150ms
ANSI09000976 V2 EN
Figure 227: Simplified logic scheme of the CCRBRF (50BF) starting logic
AND
AND
AND
AND
AND
OR
OR
OR
a
b
a>b
AND
a
b
a>b
AND
Time out A
BFP Started A
Reset A
52a_A
I_A
Current High A
Contact Closed A
ANSI09000977-1-en.vsd
FunctionMode
OR
OR
Current
Contact
Current and Contact
1
CB Closed A
Pickup_PH
Pickup_BlkCont
ANSI09000977 V1 EN
Figure 228: Simplified logic scheme of the CCRBRF (50BF), CB position evaluation
Section 7 1MRK505222-UUS C
Current protection
458
Technical reference manual
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