Tau
: The thermal time constant of the protected circuit given in minutes. Please
refer to manufacturers manuals for details.
TripTemp
: Temperature value for trip of the protected circuit. For cables, a
maximum allowed conductor temperature is often stated to be 90°C (194°F). For
overhead lines, the critical temperature for aluminium conductor is about 90 -
100°C (194-212°F). For a copper conductor a normal figure is 70°C (158°F).
AlarmTemp
: Temperature level for alarm of the protected circuit. ALARM signal
can be used as a warning before the circuit is tripped. Therefore the setting shall be
lower than the trip level. It shall at the same time be higher than the maximum
conductor temperature at normal operation. For cables this level is often given to
65°C (149°F). Similar values are stated for overhead lines. A suitable setting can
be about 15°C (59°F) below the trip value.
ReclTemp
: Temperature where lockout signal LOCKOUT from the protection is
released. When the thermal overload protection trips, a lock-out signal is activated.
This signal is intended to block switch in of the protected circuit as long as the
conductor temperature is high. The signal is released when the estimated
temperature is below the set value. This temperature value should be chosen below
the alarm temperature.
8.6
Breaker failure protection CCRBRF
IP14514-1 v6
8.6.1
Identification
M14878-1 v5
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Breaker failure protection, 3-phase
activation and output
CCRBRF
3I>BF
SYMBOL-U V1 EN-US
50BF
8.6.2
Application
M13916-3 v7
In the design of the fault clearance system the N-1 criterion is often used. This
means that a fault needs to be cleared even if any component in the fault clearance
system is faulty. One necessary component in the fault clearance system is the
circuit breaker. It is from practical and economical reason not feasible to duplicate
the circuit breaker for the protected object. Instead a breaker failure protection is
used.
Breaker failure protection, 3-phase activation and output (CCRBRF) will issue a
back-up trip command to adjacent circuit breakers in case of failure to trip of the
Section 8
1MRK 505 393-UEN B
Current protection
182
Line differential protection RED650 2.2 IEC
Application manual
Summary of Contents for RED650
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