2.26 Breaker Failure Protection (ANSI 50BF)
159
7UM61 Manual
C53000-G1176-C127-3
Figure 2-58
Logic Diagram of the Breaker Failure Protection
2.26.2 Setting Notes
General
Breaker failure protection is only effective and available if address
170
BREAKER
FAILURE
is set to
Enabled
during configuration. If the function is not required
Disabled
is set. Address
7001
BREAKER FAILURE
serves to switch the function
ON
or
OFF
or to block only the trip command (
Block relay
).
Criteria
The parameter
7002
TRIP INTERN
serves to select the OFF criterion of an internal
pickup. It can be implemented by reading the switching status of the output relay BA3
provided for this (
7002
TRIP INTERN
=
BO3
) or by a logic link created in CFC (=
CFC
)
(message 1442
“>int. start B/F”
). It can also be completely deactivated (
7002
TRIP INTERN
=
OFF
). In this case only external sources have effect.
Note: Be aware that only the potential-free binary output
BO3
(relay BO3) can be used
for the breaker failure protection. This means that trippings for the mains breaker (or
the particular breaker being monitored) must be configured to this binary output.
The pickup threshold
7003
CIRC. BR. I>
setting of the current criterion applies for
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.
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