ABB RELION REX640 Technical Manual page 1525

1MRS759142 C
REX640
Technical Manual
FALSE, provided that the circuit breaker is closed. The reclose command pulse time
can be controlled with the Close pulse time setting: the CLOSE_CB output is active for
the time set with the Close pulse time setting. The CLOSE_CB output is deactivated
also when the circuit breaker is detected to be closed, that is, when the CB_POS input
changes from open state to closed state. The Wait close time setting defines the time
after the CLOSE_CB command activation, during which the circuit breaker should be
closed. If the closing of circuit breaker does not happen during this time, the
autoreclosing function is driven to lockout or, if allowed, an auto-initiation is
activated.
The main motivation for autoreclosing to begin with is the assumption that the fault is
temporary by nature, and that a momentary de-energizing of the power line and an
automatic reclosing restores the power supply. However, when the power line is
manually energized and an immediate protection trip is detected, it is very likely that
the fault is of a permanent type. A permanent fault is, for example, energizing a power
line into a forgotten earthing after a maintenance work along the power line. In such
cases, SOTF is activated, but only for the reclaim time after energizing the power line
and only when the circuit breaker is closed manually and not by the AR function.
SOTF disables any initiation of an autoreclosing shot. The energizing of the power
line is detected from the CB_POS information.
SOTF is activated when the AR function is enabled or when the AR function is started
and the SOTF should remain active for the reclaim time.
When SOTF is detected, the parameter SOTF is active.
If the Manual close mode setting is set to FALSE and the circuit
breaker has been manually closed during an autoreclosing shot, the
AR unit goes to an immediate lockout.
If the Manual close mode setting is set to TRUE and the circuit breaker
has been manually closed during an autoreclosing shot (the INPRO is
active), the shot is considered as completed.
When SOTF starts, reclaim time is restarted, provided that it is
running.
The frequent-operation counter is intended for blocking the autoreclosing function in
cases where the fault causes repetitive autoreclosing sequences during a short period
of time. For instance, if a tree causes a short circuit and, as a result, there are
autoreclosing shots within a few minutes interval during a stormy night. These types
of faults can easily damage the circuit breaker if the AR function is not locked by a
frequent-operation counter.
The frequent-operation counter has three settings:
Section 9
Control functions
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