Siemens 7SC80 - Settings

Criteria
Address 7004 Chk BRK CONTACT establishes whether or not the breaker auxiliary contacts connected via
binary inputs are to be used as a criterion for pickup. If this address is set to ON, then current criterion and/or
the auxiliary contact criterion apply. This setting must be selected if the breaker failure protection is started by
functions, which do not always have a certain criterion for detection of an open circuit breaker, e.g. voltage
protection.
Time Delay
The time delay is entered at address 7005 TRIP-Timer. This setting should be based on the maximum circuit
breaker operating time plus the dropout time of the current flow monitoring element plus a safety margin
which takes into consideration the tolerance of the time delay. In case of an external start, the set time delay
is reduced automatically by 10 ms in order to compensate the residual time of the external start.Figure 2-108
illustrates the time sequences.
[abl-bei-norm-fehlerkllaer-u-bei-lsvs-20061220, 1, en_US]
Figure 2-108 Time sequence example for normal clearance of a fault, and with circuit breaker failure
Pickup Values
The pickup value of the current flow monitoring is set under address 7006 50BF PICKUP, and the pickup
value of the ground current monitoring under address 7007 50BF PICKUP IE>. The threshold values must
be set at a level below the minimum fault current for which the total current monitoring must operate. A
setting of 10 % below the minimum fault current for which breaker failure protection must operate is recom-
mended. The pickup value should not be set too low since otherwise there is a risk that transients in the
current transformer secondary circuit may lead to extended dropout times if extremely high currents are
switched off.
Settings
The table indicates region-specific presettings. Column C (configuration) indicates the corresponding secon-
dary nominal current of the current transformer.
Addr.
Parameter C Setting Options Default Setting Comments
7001 FCT 50BF OFF
ON
OFF 50BF Breaker Failure
Protection
7004 Chk BRK CONTACT OFF
ON
OFF Check Breaker contacts
7005 TRIP-Timer 0.06 .. 60.00 sec; ∞ 0.25 sec TRIP-Timer
7006 50BF PICKUP 1A 0.05 .. 20.00 A 0.10 A 50BF Pickup current
threshold
5A 0.25 .. 100.00 A 0.50 A
7007 50BF PICKUP IE> 1A 0.05 .. 20.00 A 0.10 A 50BF Pickup earth current
threshold
5A 0.25 .. 100.00 A 0.50 A
2.18.3
Functions
2.18 Breaker Failure Protection 50BF
SIPROTEC Compact, 7SC80, Manual 321
E50417-G1140-C486-A8, Edition 07.2017