Settings For Breaker Failure Protection - Siemens Siprotec 7UM62 Manual

Functions
Time Delay

2.34.2.1 Settings for Breaker Failure Protection

Addr. Setting Title
7001 BREAKER
FAILURE
7002 TRIP INTERN
7003 CIRC. BR. I>
7004 TRIP-Timer
228
The pickup threshold 7003 CIRC. BR. I> setting of the current criterion refers to
all three phases. The user must select a value ensuring that the function still picks up
even for the lowest operating current to be expected. For this reason, the value should
be set at least 10% below the minimum operating current.
However, the pick-up value should not be selected lower than necessary, as a too
sensitive setting risks prolongations of the drop-out time due to balancing procedures
in the current transformer secondary circuit during the switchoff of too high currents.
The breaker failure time delay setting is entered at 7004 TRIP-Timer. This setting
should be based on the circuit breaker interrupting time plus the dropout time of the
current flow monitoring element plus a safety margin. Figure 2-110 illustrates the
timing of a typical breaker failure scenario.
Fault occurs
Normal fault clearing time
Trip.
time
Breaker disconnecting time
Breaker failure
pickup
Total fault clearing time for breaker failure condition
Figure 2-110 Timing for a Typical Breaker Failure Scenario
The following list indicates the setting ranges and the default settings of a I
secondary nominal current. For a secondary nominal current of I
must be multiplied by 5. Consider the current transformer ratios when setting the
device with primary values.
Setting Options
OFF
ON
Block relay for trip com-
mands
OFF
Start Breaker Failure with
Bin.Outp.12
Start Breaker Failure with
CFC
0.04..2.00 A
0.06..60.00 sec; ∞
Dropout
CIRC.
BR. I>
Delay time TRIP-Timer
Breaker failure monitoring
Default Setting
OFF
OFF
0.20 A
0.25 sec
Safety
time
Breaker
disconnecting time
(adjacent)
N
= 5 A, these values
N
Comments
Breaker Failure Protection
Start with Internal TRIP Com-
mand
Supervision Current Pickup
TRIP-Timer
7UM62 Manual
C53000-G1176-C149-3
= 1 A