Functions
228
7UM62 Manual
C53000-G1176-C149-3
The pickup threshold
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.
Time Delay
The breaker failure time delay setting is entered at
. 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.
Figure 2-110 Timing for a Typical Breaker Failure Scenario
2.34.2.1 Settings for Breaker Failure Protection
The following list indicates the setting ranges and the default settings of a I
N
= 1 A
secondary nominal current. For a secondary nominal current of I
N
= 5 A, these values
must be multiplied by 5. Consider the current transformer ratios when setting the
device with primary values.
Normal fault clearing time
Trip.
time
Fault occurs
Breaker disconnecting time
Dropout
Safety
time
Breaker failure
pickup
Delay time
Breaker failure monitoring
Breaker
disconnecting time
(adjacent)
Total fault clearing time for breaker failure condition
Addr.
Setting Title
Setting Options
Default Setting
Comments
7001
BREAKER
FAILURE
OFF
ON
Block relay for trip com-
mands
OFF
Breaker Failure Protection
7002
TRIP INTERN
OFF
Start Breaker Failure with
Bin.Outp.12
Start Breaker Failure with
CFC
OFF
Start with Internal TRIP Com-
mand
7003
CIRC. BR. I>
0.04..2.00 A
0.20 A
Supervision Current Pickup
7004
TRIP-Timer
0.06..60.00 sec;
∞
0.25 sec
TRIP-Timer
