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Figure 2-58
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).
The parameter 7002 TRIP INTERN serves to select the OFF criterion of an internal
Criteria
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.
7UM61 Manual
C53000-G1176-C127-3
Logic Diagram of the Breaker Failure Protection
2.26 Breaker Failure Protection (ANSI 50BF)
159
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